Agent SDK reference - Python
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Documentation Index
Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt Use this file to discover all available pages before exploring further.
Agent SDK reference - Python
Complete API reference for the Python Agent SDK, including all functions, types, and classes.
Installation
```bash theme={null} pip install claude-agent-sdk
## Choosing between `query()` and `ClaudeSDKClient`
The Python SDK provides two ways to interact with Claude Code:
### Quick comparison
| Feature | `query()` | `ClaudeSDKClient` |
| :------------------ | :---------------------------- | :--------------------------------- |
| **Session** | Creates new session each time | Reuses same session |
| **Conversation** | Single exchange | Multiple exchanges in same context |
| **Connection** | Managed automatically | Manual control |
| **Streaming Input** | ✅ Supported | ✅ Supported |
| **Interrupts** | ❌ Not supported | ✅ Supported |
| **Hooks** | ✅ Supported | ✅ Supported |
| **Custom Tools** | ✅ Supported | ✅ Supported |
| **Continue Chat** | ❌ New session each time | ✅ Maintains conversation |
| **Use Case** | One-off tasks | Continuous conversations |
### When to use `query()` (new session each time)
**Best for:**
* One-off questions where you don't need conversation history
* Independent tasks that don't require context from previous exchanges
* Simple automation scripts
* When you want a fresh start each time
### When to use `ClaudeSDKClient` (continuous conversation)
**Best for:**
* **Continuing conversations** - When you need Claude to remember context
* **Follow-up questions** - Building on previous responses
* **Interactive applications** - Chat interfaces, REPLs
* **Response-driven logic** - When next action depends on Claude's response
* **Session control** - Managing conversation lifecycle explicitly
## Functions
### `query()`
Creates a new session for each interaction with Claude Code. Returns an async iterator that yields messages as they arrive. Each call to `query()` starts fresh with no memory of previous interactions.
```python theme={null}
async def query(
*,
prompt: str | AsyncIterable[dict[str, Any]],
options: ClaudeAgentOptions | None = None,
transport: Transport | None = None
) -> AsyncIterator[Message]
Parameters
| Parameter | Type | Description |
|---|---|---|
prompt |
str \| AsyncIterable[dict] |
The input prompt as a string or async iterable for streaming mode |
options |
ClaudeAgentOptions \| None |
Optional configuration object (defaults to ClaudeAgentOptions() if None) |
transport |
Transport \| None |
Optional custom transport for communicating with the CLI process |
Returns
Returns an AsyncIterator[Message] that yields messages from the conversation.
Example - With options
```python theme={null} import asyncio from claude_agent_sdk import query, ClaudeAgentOptions
async def main(): options = ClaudeAgentOptions( system_prompt="You are an expert Python developer", permission_mode="acceptEdits", cwd="/home/user/project", )
async for message in query(prompt="Create a Python web server", options=options):
print(message)
asyncio.run(main())
### `tool()`
Decorator for defining MCP tools with type safety.
```python theme={null}
def tool(
name: str,
description: str,
input_schema: type | dict[str, Any],
annotations: ToolAnnotations | None = None
) -> Callable[[Callable[[Any], Awaitable[dict[str, Any]]]], SdkMcpTool[Any]]
Parameters
| Parameter | Type | Description |
|---|---|---|
name |
str |
Unique identifier for the tool |
description |
str |
Human-readable description of what the tool does |
input_schema |
type \| dict[str, Any] |
Schema defining the tool's input parameters (see below) |
annotations |
ToolAnnotations\| None |
Optional MCP tool annotations providing behavioral hints to clients |
Input schema options
- Simple type mapping (recommended):
python theme={null}
{"text": str, "count": int, "enabled": bool}
- JSON Schema format (for complex validation):
python theme={null} { "type": "object", "properties": { "text": {"type": "string"}, "count": {"type": "integer", "minimum": 0}, }, "required": ["text"], }
Returns
A decorator function that wraps the tool implementation and returns an SdkMcpTool instance.
Example
```python theme={null} from claude_agent_sdk import tool from typing import Any
@tool("greet", "Greet a user", {"name": str}) async def greet(args: dict[str, Any]) -> dict[str, Any]: return {"content": [{"type": "text", "text": f"Hello, {args['name']}!"}]}
#### `ToolAnnotations`
Re-exported from `mcp.types` (also available as `from claude_agent_sdk import ToolAnnotations`). All fields are optional hints; clients should not rely on them for security decisions.
| Field | Type | Default | Description |
| :---------------- | :------------- | :------ | :--------------------------------------------------------------------------------------------------------------------------------------------------- |
| `title` | `str \| None` | `None` | Human-readable title for the tool |
| `readOnlyHint` | `bool \| None` | `False` | If `True`, the tool does not modify its environment |
| `destructiveHint` | `bool \| None` | `True` | If `True`, the tool may perform destructive updates (only meaningful when `readOnlyHint` is `False`) |
| `idempotentHint` | `bool \| None` | `False` | If `True`, repeated calls with the same arguments have no additional effect (only meaningful when `readOnlyHint` is `False`) |
| `openWorldHint` | `bool \| None` | `True` | If `True`, the tool interacts with external entities (for example, web search). If `False`, the tool's domain is closed (for example, a memory tool) |
```python theme={null}
from claude_agent_sdk import tool, ToolAnnotations
from typing import Any
@tool(
"search",
"Search the web",
{"query": str},
annotations=ToolAnnotations(readOnlyHint=True, openWorldHint=True),
)
async def search(args: dict[str, Any]) -> dict[str, Any]:
return {"content": [{"type": "text", "text": f"Results for: {args['query']}"}]}
create_sdk_mcp_server()
Create an in-process MCP server that runs within your Python application.
```python theme={null} def create_sdk_mcp_server( name: str, version: str = "1.0.0", tools: list[SdkMcpTool[Any]] | None = None ) -> McpSdkServerConfig
#### Parameters
| Parameter | Type | Default | Description |
| :-------- | :------------------------------ | :-------- | :---------------------------------------------------- |
| `name` | `str` | - | Unique identifier for the server |
| `version` | `str` | `"1.0.0"` | Server version string |
| `tools` | `list[SdkMcpTool[Any]] \| None` | `None` | List of tool functions created with `@tool` decorator |
#### Returns
Returns an `McpSdkServerConfig` object that can be passed to `ClaudeAgentOptions.mcp_servers`.
#### Example
```python theme={null}
from claude_agent_sdk import tool, create_sdk_mcp_server
@tool("add", "Add two numbers", {"a": float, "b": float})
async def add(args):
return {"content": [{"type": "text", "text": f"Sum: {args['a'] + args['b']}"}]}
@tool("multiply", "Multiply two numbers", {"a": float, "b": float})
async def multiply(args):
return {"content": [{"type": "text", "text": f"Product: {args['a'] * args['b']}"}]}
calculator = create_sdk_mcp_server(
name="calculator",
version="2.0.0",
tools=[add, multiply], # Pass decorated functions
)
# Use with Claude
options = ClaudeAgentOptions(
mcp_servers={"calc": calculator},
allowed_tools=["mcp__calc__add", "mcp__calc__multiply"],
)
list_sessions()
Lists past sessions with metadata. Filter by project directory or list sessions across all projects. Synchronous; returns immediately.
```python theme={null} def list_sessions( directory: str | None = None, limit: int | None = None, include_worktrees: bool = True ) -> list[SDKSessionInfo]
#### Parameters
| Parameter | Type | Default | Description |
| :------------------ | :------------ | :------ | :------------------------------------------------------------------------------------ |
| `directory` | `str \| None` | `None` | Directory to list sessions for. When omitted, returns sessions across all projects |
| `limit` | `int \| None` | `None` | Maximum number of sessions to return |
| `include_worktrees` | `bool` | `True` | When `directory` is inside a git repository, include sessions from all worktree paths |
#### Return type: `SDKSessionInfo`
| Property | Type | Description |
| :-------------- | :------------ | :------------------------------------------------------------------- |
| `session_id` | `str` | Unique session identifier |
| `summary` | `str` | Display title: custom title, auto-generated summary, or first prompt |
| `last_modified` | `int` | Last modified time in milliseconds since epoch |
| `file_size` | `int \| None` | Session file size in bytes (`None` for remote storage backends) |
| `custom_title` | `str \| None` | User-set session title |
| `first_prompt` | `str \| None` | First meaningful user prompt in the session |
| `git_branch` | `str \| None` | Git branch at the end of the session |
| `cwd` | `str \| None` | Working directory for the session |
| `tag` | `str \| None` | User-set session tag (see [`tag_session()`](#tag-session)) |
| `created_at` | `int \| None` | Session creation time in milliseconds since epoch |
#### Example
Print the 10 most recent sessions for a project. Results are sorted by `last_modified` descending, so the first item is the newest. Omit `directory` to search across all projects.
```python theme={null}
from claude_agent_sdk import list_sessions
for session in list_sessions(directory="/path/to/project", limit=10):
print(f"{session.summary} ({session.session_id})")
get_session_messages()
Retrieves messages from a past session. Synchronous; returns immediately.
```python theme={null} def get_session_messages( session_id: str, directory: str | None = None, limit: int | None = None, offset: int = 0 ) -> list[SessionMessage]
#### Parameters
| Parameter | Type | Default | Description |
| :----------- | :------------ | :------- | :---------------------------------------------------------------- |
| `session_id` | `str` | required | The session ID to retrieve messages for |
| `directory` | `str \| None` | `None` | Project directory to look in. When omitted, searches all projects |
| `limit` | `int \| None` | `None` | Maximum number of messages to return |
| `offset` | `int` | `0` | Number of messages to skip from the start |
#### Return type: `SessionMessage`
| Property | Type | Description |
| :------------------- | :----------------------------- | :------------------------ |
| `type` | `Literal["user", "assistant"]` | Message role |
| `uuid` | `str` | Unique message identifier |
| `session_id` | `str` | Session identifier |
| `message` | `Any` | Raw message content |
| `parent_tool_use_id` | `None` | Reserved for future use |
#### Example
```python theme={null}
from claude_agent_sdk import list_sessions, get_session_messages
sessions = list_sessions(limit=1)
if sessions:
messages = get_session_messages(sessions[0].session_id)
for msg in messages:
print(f"[{msg.type}] {msg.uuid}")
get_session_info()
Reads metadata for a single session by ID without scanning the full project directory. Synchronous; returns immediately.
```python theme={null} def get_session_info( session_id: str, directory: str | None = None, ) -> SDKSessionInfo | None
#### Parameters
| Parameter | Type | Default | Description |
| :----------- | :------------ | :------- | :--------------------------------------------------------------------- |
| `session_id` | `str` | required | UUID of the session to look up |
| `directory` | `str \| None` | `None` | Project directory path. When omitted, searches all project directories |
Returns [`SDKSessionInfo`](#return-type-sdk-session-info), or `None` if the session is not found.
#### Example
Look up a single session's metadata without scanning the project directory. Useful when you already have a session ID from a previous run.
```python theme={null}
from claude_agent_sdk import get_session_info
info = get_session_info("550e8400-e29b-41d4-a716-446655440000")
if info:
print(f"{info.summary} (branch: {info.git_branch}, tag: {info.tag})")
rename_session()
Renames a session by appending a custom-title entry. Repeated calls are safe; the most recent title wins. Synchronous.
```python theme={null} def rename_session( session_id: str, title: str, directory: str | None = None, ) -> None
#### Parameters
| Parameter | Type | Default | Description |
| :----------- | :------------ | :------- | :--------------------------------------------------------------------- |
| `session_id` | `str` | required | UUID of the session to rename |
| `title` | `str` | required | New title. Must be non-empty after stripping whitespace |
| `directory` | `str \| None` | `None` | Project directory path. When omitted, searches all project directories |
Raises `ValueError` if `session_id` is not a valid UUID or `title` is empty; `FileNotFoundError` if the session cannot be found.
#### Example
Rename the most recent session so it's easier to find later. The new title appears in [`SDKSessionInfo.custom_title`](#return-type-sdk-session-info) on subsequent reads.
```python theme={null}
from claude_agent_sdk import list_sessions, rename_session
sessions = list_sessions(directory="/path/to/project", limit=1)
if sessions:
rename_session(sessions[0].session_id, "Refactor auth module")
tag_session()
Tags a session. Pass None to clear the tag. Repeated calls are safe; the most recent tag wins. Synchronous.
```python theme={null} def tag_session( session_id: str, tag: str | None, directory: str | None = None, ) -> None
#### Parameters
| Parameter | Type | Default | Description |
| :----------- | :------------ | :------- | :--------------------------------------------------------------------- |
| `session_id` | `str` | required | UUID of the session to tag |
| `tag` | `str \| None` | required | Tag string, or `None` to clear. Unicode-sanitized before storing |
| `directory` | `str \| None` | `None` | Project directory path. When omitted, searches all project directories |
Raises `ValueError` if `session_id` is not a valid UUID or `tag` is empty after sanitization; `FileNotFoundError` if the session cannot be found.
#### Example
Tag a session, then filter by that tag on a later read. Pass `None` to clear an existing tag.
```python theme={null}
from claude_agent_sdk import list_sessions, tag_session
# Tag a session
tag_session("550e8400-e29b-41d4-a716-446655440000", "needs-review")
# Later: find all sessions with that tag
for session in list_sessions(directory="/path/to/project"):
if session.tag == "needs-review":
print(session.summary)
Classes
ClaudeSDKClient
Maintains a conversation session across multiple exchanges. This is the Python equivalent of how the TypeScript SDK's query() function works internally - it creates a client object that can continue conversations.
Key Features
- Session continuity: Maintains conversation context across multiple
query()calls - Same conversation: The session retains previous messages
- Interrupt support: Can stop execution mid-task
- Explicit lifecycle: You control when the session starts and ends
- Response-driven flow: Can react to responses and send follow-ups
- Custom tools and hooks: Supports custom tools (created with
@tooldecorator) and hooks
```python theme={null} class ClaudeSDKClient: def init(self, options: ClaudeAgentOptions | None = None, transport: Transport | None = None) async def connect(self, prompt: str | AsyncIterable[dict] | None = None) -> None async def query(self, prompt: str | AsyncIterable[dict], session_id: str = "default") -> None async def receive_messages(self) -> AsyncIterator[Message] async def receive_response(self) -> AsyncIterator[Message] async def interrupt(self) -> None async def set_permission_mode(self, mode: str) -> None async def set_model(self, model: str | None = None) -> None async def rewind_files(self, user_message_id: str) -> None async def get_mcp_status(self) -> McpStatusResponse async def reconnect_mcp_server(self, server_name: str) -> None async def toggle_mcp_server(self, server_name: str, enabled: bool) -> None async def stop_task(self, task_id: str) -> None async def get_server_info(self) -> dict[str, Any] | None async def disconnect(self) -> None
#### Methods
| Method | Description |
| :---------------------------------------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `__init__(options)` | Initialize the client with optional configuration |
| `connect(prompt)` | Connect to Claude with an optional initial prompt or message stream |
| `query(prompt, session_id)` | Send a new request in streaming mode |
| `receive_messages()` | Receive all messages from Claude as an async iterator |
| `receive_response()` | Receive messages until and including a ResultMessage |
| `interrupt()` | Send interrupt signal (only works in streaming mode) |
| `set_permission_mode(mode)` | Change the permission mode for the current session |
| `set_model(model)` | Change the model for the current session. Pass `None` to reset to default |
| `rewind_files(user_message_id)` | Restore files to their state at the specified user message. Requires `enable_file_checkpointing=True`. See [File checkpointing](https://code.claude.com/en/agent-sdk/file-checkpointing) |
| `get_mcp_status()` | Get the status of all configured MCP servers. Returns [`McpStatusResponse`](#mcp-status-response) |
| `reconnect_mcp_server(server_name)` | Retry connecting to an MCP server that failed or was disconnected |
| `toggle_mcp_server(server_name, enabled)` | Enable or disable an MCP server mid-session. Disabling removes its tools |
| `stop_task(task_id)` | Stop a running background task. A [`TaskNotificationMessage`](#task-notification-message) with status `"stopped"` follows in the message stream |
| `get_server_info()` | Get server information including session ID and capabilities |
| `disconnect()` | Disconnect from Claude |
#### Context Manager Support
The client can be used as an async context manager for automatic connection management:
```python theme={null}
async with ClaudeSDKClient() as client:
await client.query("Hello Claude")
async for message in client.receive_response():
print(message)
Important: When iterating over messages, avoid using
breakto exit early as this can cause asyncio cleanup issues. Instead, let the iteration complete naturally or use flags to track when you've found what you need.
Example - Continuing a conversation
```python theme={null} import asyncio from claude_agent_sdk import ClaudeSDKClient, AssistantMessage, TextBlock, ResultMessage
async def main(): async with ClaudeSDKClient() as client: # First question await client.query("What's the capital of France?")
# Process response
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Claude: {block.text}")
# Follow-up question - the session retains the previous context
await client.query("What's the population of that city?")
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Claude: {block.text}")
# Another follow-up - still in the same conversation
await client.query("What are some famous landmarks there?")
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Claude: {block.text}")
asyncio.run(main())
#### Example - Streaming input with ClaudeSDKClient
```python theme={null}
import asyncio
from claude_agent_sdk import ClaudeSDKClient
async def message_stream():
"""Generate messages dynamically."""
yield {
"type": "user",
"message": {"role": "user", "content": "Analyze the following data:"},
}
await asyncio.sleep(0.5)
yield {
"type": "user",
"message": {"role": "user", "content": "Temperature: 25°C, Humidity: 60%"},
}
await asyncio.sleep(0.5)
yield {
"type": "user",
"message": {"role": "user", "content": "What patterns do you see?"},
}
async def main():
async with ClaudeSDKClient() as client:
# Stream input to Claude
await client.query(message_stream())
# Process response
async for message in client.receive_response():
print(message)
# Follow-up in same session
await client.query("Should we be concerned about these readings?")
async for message in client.receive_response():
print(message)
asyncio.run(main())
Example - Using interrupts
```python theme={null} import asyncio from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions, ResultMessage
async def interruptible_task(): options = ClaudeAgentOptions(allowed_tools=["Bash"], permission_mode="acceptEdits")
async with ClaudeSDKClient(options=options) as client:
# Start a long-running task
await client.query("Count from 1 to 100 slowly, using the bash sleep command")
# Let it run for a bit
await asyncio.sleep(2)
# Interrupt the task
await client.interrupt()
print("Task interrupted!")
# Drain the interrupted task's messages (including its ResultMessage)
async for message in client.receive_response():
if isinstance(message, ResultMessage):
print(f"Interrupted task finished with subtype={message.subtype!r}")
# subtype is "error_during_execution" for interrupted tasks
# Send a new command
await client.query("Just say hello instead")
# Now receive the new response
async for message in client.receive_response():
if isinstance(message, ResultMessage) and message.subtype == "success":
print(f"New result: {message.result}")
asyncio.run(interruptible_task())
<Note>
**Buffer behavior after interrupt:** `interrupt()` sends a stop signal but does not clear the message buffer. Messages already produced by the interrupted task, including its `ResultMessage` (with `subtype="error_during_execution"`), remain in the stream. You must drain them with `receive_response()` before reading the response to a new query. If you send a new query immediately after `interrupt()` and call `receive_response()` only once, you'll receive the interrupted task's messages, not the new query's response.
</Note>
#### Example - Advanced permission control
```python theme={null}
from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions
from claude_agent_sdk.types import (
PermissionResultAllow,
PermissionResultDeny,
ToolPermissionContext,
)
async def custom_permission_handler(
tool_name: str, input_data: dict, context: ToolPermissionContext
) -> PermissionResultAllow | PermissionResultDeny:
"""Custom logic for tool permissions."""
# Block writes to system directories
if tool_name == "Write" and input_data.get("file_path", "").startswith("/system/"):
return PermissionResultDeny(
message="System directory write not allowed", interrupt=True
)
# Redirect sensitive file operations
if tool_name in ["Write", "Edit"] and "config" in input_data.get("file_path", ""):
safe_path = f"./sandbox/{input_data['file_path']}"
return PermissionResultAllow(
updated_input={**input_data, "file_path": safe_path}
)
# Allow everything else
return PermissionResultAllow(updated_input=input_data)
async def main():
options = ClaudeAgentOptions(
can_use_tool=custom_permission_handler, allowed_tools=["Read", "Write", "Edit"]
)
async with ClaudeSDKClient(options=options) as client:
await client.query("Update the system config file")
async for message in client.receive_response():
# Will use sandbox path instead
print(message)
asyncio.run(main())
Types
@dataclass vs TypedDict: This SDK uses two kinds of types. Classes decorated with @dataclass (such as ResultMessage, AgentDefinition, TextBlock) are object instances at runtime and support attribute access: msg.result. Classes defined with TypedDict (such as ThinkingConfigEnabled, McpStdioServerConfig, SyncHookJSONOutput) are plain dicts at runtime and require key access: config["budget_tokens"], not config.budget_tokens. The ClassName(field=value) call syntax works for both, but only dataclasses produce objects with attributes.
SdkMcpTool
Definition for an SDK MCP tool created with the @tool decorator.
```python theme={null} @dataclass class SdkMcpTool(Generic[T]): name: str description: str input_schema: type[T] | dict[str, Any] handler: Callable[[T], Awaitable[dict[str, Any]]] annotations: ToolAnnotations | None = None
| Property | Type | Description |
| :------------- | :----------------------------------------- | :--------------------------------------------------------------------------------------------------------- |
| `name` | `str` | Unique identifier for the tool |
| `description` | `str` | Human-readable description |
| `input_schema` | `type[T] \| dict[str, Any]` | Schema for input validation |
| `handler` | `Callable[[T], Awaitable[dict[str, Any]]]` | Async function that handles tool execution |
| `annotations` | `ToolAnnotations \| None` | Optional MCP tool annotations (e.g., `readOnlyHint`, `destructiveHint`, `openWorldHint`). From `mcp.types` |
### `Transport`
Abstract base class for custom transport implementations. Use this to communicate with the Claude process over a custom channel (for example, a remote connection instead of a local subprocess).
<Warning>
This is a low-level internal API. The interface may change in future releases. Custom implementations must be updated to match any interface changes.
</Warning>
```python theme={null}
from abc import ABC, abstractmethod
from collections.abc import AsyncIterator
from typing import Any
class Transport(ABC):
@abstractmethod
async def connect(self) -> None: ...
@abstractmethod
async def write(self, data: str) -> None: ...
@abstractmethod
def read_messages(self) -> AsyncIterator[dict[str, Any]]: ...
@abstractmethod
async def close(self) -> None: ...
@abstractmethod
def is_ready(self) -> bool: ...
@abstractmethod
async def end_input(self) -> None: ...
| Method | Description |
|---|---|
connect() |
Connect the transport and prepare for communication |
write(data) |
Write raw data (JSON + newline) to the transport |
read_messages() |
Async iterator that yields parsed JSON messages |
close() |
Close the connection and clean up resources |
is_ready() |
Returns True if the transport can send and receive |
end_input() |
Close the input stream (for example, close stdin for subprocess transports) |
Import: from claude_agent_sdk import Transport
ClaudeAgentOptions
Configuration dataclass for Claude Code queries.
```python theme={null} @dataclass class ClaudeAgentOptions: tools: list[str] | ToolsPreset | None = None allowed_tools: list[str] = field(default_factory=list) system_prompt: str | SystemPromptPreset | None = None mcp_servers: dict[str, McpServerConfig] | str | Path = field(default_factory=dict) permission_mode: PermissionMode | None = None continue_conversation: bool = False resume: str | None = None max_turns: int | None = None max_budget_usd: float | None = None disallowed_tools: list[str] = field(default_factory=list) model: str | None = None fallback_model: str | None = None betas: list[SdkBeta] = field(default_factory=list) output_format: dict[str, Any] | None = None permission_prompt_tool_name: str | None = None cwd: str | Path | None = None cli_path: str | Path | None = None settings: str | None = None add_dirs: list[str | Path] = field(default_factory=list) env: dict[str, str] = field(default_factory=dict) extra_args: dict[str, str | None] = field(default_factory=dict) max_buffer_size: int | None = None debug_stderr: Any = sys.stderr # Deprecated stderr: Callable[[str], None] | None = None can_use_tool: CanUseTool | None = None hooks: dict[HookEvent, list[HookMatcher]] | None = None user: str | None = None include_partial_messages: bool = False fork_session: bool = False agents: dict[str, AgentDefinition] | None = None setting_sources: list[SettingSource] | None = None sandbox: SandboxSettings | None = None plugins: list[SdkPluginConfig] = field(default_factory=list) max_thinking_tokens: int | None = None # Deprecated: use thinking instead thinking: ThinkingConfig | None = None effort: Literal["low", "medium", "high", "xhigh", "max"] | None = None enable_file_checkpointing: bool = False
| Property | Type | Default | Description |
| :---------------------------- | :--------------------------------------------------------- | :--------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `tools` | `list[str] \| ToolsPreset \| None` | `None` | Tools configuration. Use `{"type": "preset", "preset": "claude_code"}` for Claude Code's default tools |
| `allowed_tools` | `list[str]` | `[]` | Tools to auto-approve without prompting. This does not restrict Claude to only these tools; unlisted tools fall through to `permission_mode` and `can_use_tool`. Use `disallowed_tools` to block tools. See [Permissions](https://code.claude.com/en/agent-sdk/permissions#allow-and-deny-rules) |
| `system_prompt` | `str \| SystemPromptPreset \| None` | `None` | System prompt configuration. Pass a string for custom prompt, or use `{"type": "preset", "preset": "claude_code"}` for Claude Code's system prompt. Add `"append"` to extend the preset |
| `mcp_servers` | `dict[str, McpServerConfig] \| str \| Path` | `{}` | MCP server configurations or path to config file |
| `permission_mode` | `PermissionMode \| None` | `None` | Permission mode for tool usage |
| `continue_conversation` | `bool` | `False` | Continue the most recent conversation |
| `resume` | `str \| None` | `None` | Session ID to resume |
| `max_turns` | `int \| None` | `None` | Maximum agentic turns (tool-use round trips) |
| `max_budget_usd` | `float \| None` | `None` | Stop the query when the client-side cost estimate reaches this USD value. Compared against the same estimate as `total_cost_usd`; see [Track cost and usage](https://code.claude.com/en/agent-sdk/cost-tracking) for accuracy caveats |
| `disallowed_tools` | `list[str]` | `[]` | Tools to always deny. Deny rules are checked first and override `allowed_tools` and `permission_mode` (including `bypassPermissions`) |
| `enable_file_checkpointing` | `bool` | `False` | Enable file change tracking for rewinding. See [File checkpointing](https://code.claude.com/en/agent-sdk/file-checkpointing) |
| `model` | `str \| None` | `None` | Claude model to use |
| `fallback_model` | `str \| None` | `None` | Fallback model to use if the primary model fails |
| `betas` | `list[SdkBeta]` | `[]` | Beta features to enable. See [`SdkBeta`](#sdk-beta) for available options |
| `output_format` | `dict[str, Any] \| None` | `None` | Output format for structured responses (e.g., `{"type": "json_schema", "schema": {...}}`). See [Structured outputs](https://code.claude.com/en/agent-sdk/structured-outputs) for details |
| `permission_prompt_tool_name` | `str \| None` | `None` | MCP tool name for permission prompts |
| `cwd` | `str \| Path \| None` | `None` | Current working directory |
| `cli_path` | `str \| Path \| None` | `None` | Custom path to the Claude Code CLI executable |
| `settings` | `str \| None` | `None` | Path to settings file |
| `add_dirs` | `list[str \| Path]` | `[]` | Additional directories Claude can access |
| `env` | `dict[str, str]` | `{}` | Environment variables |
| `extra_args` | `dict[str, str \| None]` | `{}` | Additional CLI arguments to pass directly to the CLI |
| `max_buffer_size` | `int \| None` | `None` | Maximum bytes when buffering CLI stdout |
| `debug_stderr` | `Any` | `sys.stderr` | *Deprecated* - File-like object for debug output. Use `stderr` callback instead |
| `stderr` | `Callable[[str], None] \| None` | `None` | Callback function for stderr output from CLI |
| `can_use_tool` | [`CanUseTool`](#can-use-tool) ` \| None` | `None` | Tool permission callback function. See [Permission types](#can-use-tool) for details |
| `hooks` | `dict[HookEvent, list[HookMatcher]] \| None` | `None` | Hook configurations for intercepting events |
| `user` | `str \| None` | `None` | User identifier |
| `include_partial_messages` | `bool` | `False` | Include partial message streaming events. When enabled, [`StreamEvent`](#stream-event) messages are yielded |
| `fork_session` | `bool` | `False` | When resuming with `resume`, fork to a new session ID instead of continuing the original session |
| `agents` | `dict[str, AgentDefinition] \| None` | `None` | Programmatically defined subagents |
| `plugins` | `list[SdkPluginConfig]` | `[]` | Load custom plugins from local paths. See [Plugins](https://code.claude.com/en/agent-sdk/plugins) for details |
| `sandbox` | [`SandboxSettings`](#sandbox-settings) ` \| None` | `None` | Configure sandbox behavior programmatically. See [Sandbox settings](#sandbox-settings) for details |
| `setting_sources` | `list[SettingSource] \| None` | `None` (CLI defaults: all sources) | Control which filesystem settings to load. Pass `[]` to disable user, project, and local settings. Managed policy settings load regardless. See [Use Claude Code features](https://code.claude.com/en/agent-sdk/claude-code-features#what-settingsources-does-not-control) |
| `max_thinking_tokens` | `int \| None` | `None` | *Deprecated* - Maximum tokens for thinking blocks. Use `thinking` instead |
| `thinking` | [`ThinkingConfig`](#thinking-config) ` \| None` | `None` | Controls extended thinking behavior. Takes precedence over `max_thinking_tokens` |
| `effort` | `Literal["low", "medium", "high", "xhigh", "max"] \| None` | `None` | Effort level for thinking depth |
### `OutputFormat`
Configuration for structured output validation. Pass this as a `dict` to the `output_format` field on `ClaudeAgentOptions`:
```python theme={null}
# Expected dict shape for output_format
{
"type": "json_schema",
"schema": {...}, # Your JSON Schema definition
}
| Field | Required | Description |
|---|---|---|
type |
Yes | Must be "json_schema" for JSON Schema validation |
schema |
Yes | JSON Schema definition for output validation |
SystemPromptPreset
Configuration for using Claude Code's preset system prompt with optional additions.
```python theme={null} class SystemPromptPreset(TypedDict): type: Literal["preset"] preset: Literal["claude_code"] append: NotRequired[str] exclude_dynamic_sections: NotRequired[bool]
| Field | Required | Description |
| :------------------------- | :------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `type` | Yes | Must be `"preset"` to use a preset system prompt |
| `preset` | Yes | Must be `"claude_code"` to use Claude Code's system prompt |
| `append` | No | Additional instructions to append to the preset system prompt |
| `exclude_dynamic_sections` | No | Move per-session context such as working directory, git status, and memory paths from the system prompt into the first user message. Improves prompt-cache reuse across users and machines. See [Modify system prompts](https://code.claude.com/en/agent-sdk/modifying-system-prompts#improve-prompt-caching-across-users-and-machines) |
### `SettingSource`
Controls which filesystem-based configuration sources the SDK loads settings from.
```python theme={null}
SettingSource = Literal["user", "project", "local"]
| Value | Description | Location |
|---|---|---|
"user" |
Global user settings | ~/.claude/settings.json |
"project" |
Shared project settings (version controlled) | .claude/settings.json |
"local" |
Local project settings (gitignored) | .claude/settings.local.json |
Default behavior
When setting_sources is omitted or None, query() loads the same filesystem settings as the Claude Code CLI: user, project, and local. Managed policy settings are loaded in all cases. See What settingSources does not control for inputs that are read regardless of this option, and how to disable them.
Why use setting_sources
Disable filesystem settings:
```python theme={null}
Do not load user, project, or local settings from disk
from claude_agent_sdk import query, ClaudeAgentOptions
async for message in query( prompt="Analyze this code", options=ClaudeAgentOptions( setting_sources=[] ), ): print(message)
<Note>
In Python SDK 0.1.59 and earlier, an empty list was treated the same as omitting the option, so `setting_sources=[]` did not disable filesystem settings. Upgrade to a newer release if you need an empty list to take effect. The TypeScript SDK is not affected.
</Note>
**Load all filesystem settings explicitly:**
```python theme={null}
from claude_agent_sdk import query, ClaudeAgentOptions
async for message in query(
prompt="Analyze this code",
options=ClaudeAgentOptions(
setting_sources=["user", "project", "local"]
),
):
print(message)
Load only specific setting sources:
```python theme={null}
Load only project settings, ignore user and local
async for message in query( prompt="Run CI checks", options=ClaudeAgentOptions( setting_sources=["project"] # Only .claude/settings.json ), ): print(message)
**Testing and CI environments:**
```python theme={null}
# Ensure consistent behavior in CI by excluding local settings
async for message in query(
prompt="Run tests",
options=ClaudeAgentOptions(
setting_sources=["project"], # Only team-shared settings
permission_mode="bypassPermissions",
),
):
print(message)
SDK-only applications:
```python theme={null}
Define everything programmatically.
Pass [] to opt out of filesystem setting sources.
async for message in query( prompt="Review this PR", options=ClaudeAgentOptions( setting_sources=[], agents={...}, mcp_servers={...}, allowed_tools=["Read", "Grep", "Glob"], ), ): print(message)
**Loading CLAUDE.md project instructions:**
```python theme={null}
# Load project settings to include CLAUDE.md files
async for message in query(
prompt="Add a new feature following project conventions",
options=ClaudeAgentOptions(
system_prompt={
"type": "preset",
"preset": "claude_code", # Use Claude Code's system prompt
},
setting_sources=["project"], # Loads CLAUDE.md from project
allowed_tools=["Read", "Write", "Edit"],
),
):
print(message)
Settings precedence
When multiple sources are loaded, settings are merged with this precedence (highest to lowest):
- Local settings (
.claude/settings.local.json) - Project settings (
.claude/settings.json) - User settings (
~/.claude/settings.json)
Programmatic options such as agents and allowed_tools override user, project, and local filesystem settings. Managed policy settings take precedence over programmatic options.
AgentDefinition
Configuration for a subagent defined programmatically.
```python theme={null} @dataclass class AgentDefinition: description: str prompt: str tools: list[str] | None = None model: Literal["sonnet", "opus", "haiku", "inherit"] | None = None skills: list[str] | None = None memory: Literal["user", "project", "local"] | None = None mcpServers: list[str | dict[str, Any]] | None = None
| Field | Required | Description |
| :------------ | :------- | :-------------------------------------------------------------------------------------------------- |
| `description` | Yes | Natural language description of when to use this agent |
| `prompt` | Yes | The agent's system prompt |
| `tools` | No | Array of allowed tool names. If omitted, inherits all tools |
| `model` | No | Model override for this agent. If omitted, uses the main model |
| `skills` | No | List of skill names available to this agent |
| `memory` | No | Memory source for this agent: `"user"`, `"project"`, or `"local"` |
| `mcpServers` | No | MCP servers available to this agent. Each entry is a server name or an inline `{name: config}` dict |
### `PermissionMode`
Permission modes for controlling tool execution.
```python theme={null}
PermissionMode = Literal[
"default", # Standard permission behavior
"acceptEdits", # Auto-accept file edits
"plan", # Planning mode - no execution
"dontAsk", # Deny anything not pre-approved instead of prompting
"bypassPermissions", # Bypass all permission checks (use with caution)
]
CanUseTool
Type alias for tool permission callback functions.
```python theme={null} CanUseTool = Callable[ [str, dict[str, Any], ToolPermissionContext], Awaitable[PermissionResult] ]
The callback receives:
* `tool_name`: Name of the tool being called
* `input_data`: The tool's input parameters
* `context`: A `ToolPermissionContext` with additional information
Returns a `PermissionResult` (either `PermissionResultAllow` or `PermissionResultDeny`).
### `ToolPermissionContext`
Context information passed to tool permission callbacks.
```python theme={null}
@dataclass
class ToolPermissionContext:
signal: Any | None = None # Future: abort signal support
suggestions: list[PermissionUpdate] = field(default_factory=list)
| Field | Type | Description |
|---|---|---|
signal |
Any \| None |
Reserved for future abort signal support |
suggestions |
list[PermissionUpdate] |
Permission update suggestions from the CLI |
PermissionResult
Union type for permission callback results.
```python theme={null} PermissionResult = PermissionResultAllow | PermissionResultDeny
### `PermissionResultAllow`
Result indicating the tool call should be allowed.
```python theme={null}
@dataclass
class PermissionResultAllow:
behavior: Literal["allow"] = "allow"
updated_input: dict[str, Any] | None = None
updated_permissions: list[PermissionUpdate] | None = None
| Field | Type | Default | Description |
|---|---|---|---|
behavior |
Literal["allow"] |
"allow" |
Must be "allow" |
updated_input |
dict[str, Any] \| None |
None |
Modified input to use instead of original |
updated_permissions |
list[PermissionUpdate] \| None |
None |
Permission updates to apply |
PermissionResultDeny
Result indicating the tool call should be denied.
```python theme={null} @dataclass class PermissionResultDeny: behavior: Literal["deny"] = "deny" message: str = "" interrupt: bool = False
| Field | Type | Default | Description |
| :---------- | :---------------- | :------- | :----------------------------------------- |
| `behavior` | `Literal["deny"]` | `"deny"` | Must be "deny" |
| `message` | `str` | `""` | Message explaining why the tool was denied |
| `interrupt` | `bool` | `False` | Whether to interrupt the current execution |
### `PermissionUpdate`
Configuration for updating permissions programmatically.
```python theme={null}
@dataclass
class PermissionUpdate:
type: Literal[
"addRules",
"replaceRules",
"removeRules",
"setMode",
"addDirectories",
"removeDirectories",
]
rules: list[PermissionRuleValue] | None = None
behavior: Literal["allow", "deny", "ask"] | None = None
mode: PermissionMode | None = None
directories: list[str] | None = None
destination: (
Literal["userSettings", "projectSettings", "localSettings", "session"] | None
) = None
| Field | Type | Description |
|---|---|---|
type |
Literal[...] |
The type of permission update operation |
rules |
list[PermissionRuleValue] \| None |
Rules for add/replace/remove operations |
behavior |
Literal["allow", "deny", "ask"] \| None |
Behavior for rule-based operations |
mode |
PermissionMode \| None |
Mode for setMode operation |
directories |
list[str] \| None |
Directories for add/remove directory operations |
destination |
Literal[...] \| None |
Where to apply the permission update |
PermissionRuleValue
A rule to add, replace, or remove in a permission update.
```python theme={null} @dataclass class PermissionRuleValue: tool_name: str rule_content: str | None = None
### `ToolsPreset`
Preset tools configuration for using Claude Code's default tool set.
```python theme={null}
class ToolsPreset(TypedDict):
type: Literal["preset"]
preset: Literal["claude_code"]
ThinkingConfig
Controls extended thinking behavior. A union of three configurations:
```python theme={null} class ThinkingConfigAdaptive(TypedDict): type: Literal["adaptive"]
class ThinkingConfigEnabled(TypedDict): type: Literal["enabled"] budget_tokens: int
class ThinkingConfigDisabled(TypedDict): type: Literal["disabled"]
ThinkingConfig = ThinkingConfigAdaptive | ThinkingConfigEnabled | ThinkingConfigDisabled
| Variant | Fields | Description |
| :--------- | :---------------------- | :------------------------------------------- |
| `adaptive` | `type` | Claude adaptively decides when to think |
| `enabled` | `type`, `budget_tokens` | Enable thinking with a specific token budget |
| `disabled` | `type` | Disable thinking |
Because these are `TypedDict` classes, they're plain dicts at runtime. Either construct them as dict literals or call the class like a constructor; both produce a `dict`. Access fields with `config["budget_tokens"]`, not `config.budget_tokens`:
```python theme={null}
from claude_agent_sdk import ClaudeAgentOptions, ThinkingConfigEnabled
# Option 1: dict literal (recommended, no import needed)
options = ClaudeAgentOptions(thinking={"type": "enabled", "budget_tokens": 20000})
# Option 2: constructor-style (returns a plain dict)
config = ThinkingConfigEnabled(type="enabled", budget_tokens=20000)
print(config["budget_tokens"]) # 20000
# config.budget_tokens would raise AttributeError
SdkBeta
Literal type for SDK beta features.
```python theme={null} SdkBeta = Literal["context-1m-2025-08-07"]
Use with the `betas` field in `ClaudeAgentOptions` to enable beta features.
<Warning>
The `context-1m-2025-08-07` beta is retired as of April 30, 2026. Passing this header with Claude Sonnet 4.5 or Sonnet 4 has no effect, and requests that exceed the standard 200k-token context window return an error. To use a 1M-token context window, migrate to [Claude Sonnet 4.6, Claude Opus 4.6, or Claude Opus 4.7](https://platform.claude.com/docs/en/about-claude/models/overview), which include 1M context at standard pricing with no beta header required.
</Warning>
### `McpSdkServerConfig`
Configuration for SDK MCP servers created with `create_sdk_mcp_server()`.
```python theme={null}
class McpSdkServerConfig(TypedDict):
type: Literal["sdk"]
name: str
instance: Any # MCP Server instance
McpServerConfig
Union type for MCP server configurations.
```python theme={null} McpServerConfig = ( McpStdioServerConfig | McpSSEServerConfig | McpHttpServerConfig | McpSdkServerConfig )
#### `McpStdioServerConfig`
```python theme={null}
class McpStdioServerConfig(TypedDict):
type: NotRequired[Literal["stdio"]] # Optional for backwards compatibility
command: str
args: NotRequired[list[str]]
env: NotRequired[dict[str, str]]
McpSSEServerConfig
```python theme={null} class McpSSEServerConfig(TypedDict): type: Literal["sse"] url: str headers: NotRequired[dict[str, str]]
#### `McpHttpServerConfig`
```python theme={null}
class McpHttpServerConfig(TypedDict):
type: Literal["http"]
url: str
headers: NotRequired[dict[str, str]]
McpServerStatusConfig
The configuration of an MCP server as reported by get_mcp_status(). This is the union of all McpServerConfig transport variants plus an output-only claudeai-proxy variant for servers proxied through claude.ai.
```python theme={null} McpServerStatusConfig = ( McpStdioServerConfig | McpSSEServerConfig | McpHttpServerConfig | McpSdkServerConfigStatus | McpClaudeAIProxyServerConfig )
`McpSdkServerConfigStatus` is the serializable form of [`McpSdkServerConfig`](#mcp-sdk-server-config) with only `type` (`"sdk"`) and `name` (`str`) fields; the in-process `instance` is omitted. `McpClaudeAIProxyServerConfig` has `type` (`"claudeai-proxy"`), `url` (`str`), and `id` (`str`) fields.
### `McpStatusResponse`
Response from [`ClaudeSDKClient.get_mcp_status()`](#methods). Wraps the list of server statuses under the `mcpServers` key.
```python theme={null}
class McpStatusResponse(TypedDict):
mcpServers: list[McpServerStatus]
McpServerStatus
Status of a connected MCP server, contained in McpStatusResponse.
```python theme={null} class McpServerStatus(TypedDict): name: str status: McpServerConnectionStatus # "connected" | "failed" | "needs-auth" | "pending" | "disabled" serverInfo: NotRequired[McpServerInfo] error: NotRequired[str] config: NotRequired[McpServerStatusConfig] scope: NotRequired[str] tools: NotRequired[list[McpToolInfo]]
| Field | Type | Description |
| :----------- | :-------------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `name` | `str` | Server name |
| `status` | `str` | One of `"connected"`, `"failed"`, `"needs-auth"`, `"pending"`, or `"disabled"` |
| `serverInfo` | `dict` (optional) | Server name and version (`{"name": str, "version": str}`) |
| `error` | `str` (optional) | Error message if the server failed to connect |
| `config` | [`McpServerStatusConfig`](#mcp-server-status-config) (optional) | Server configuration. Same shape as [`McpServerConfig`](#mcp-server-config) (stdio, SSE, HTTP, or SDK), plus a `claudeai-proxy` variant for servers connected through claude.ai |
| `scope` | `str` (optional) | Configuration scope |
| `tools` | `list` (optional) | Tools provided by this server, each with `name`, `description`, and `annotations` fields |
### `SdkPluginConfig`
Configuration for loading plugins in the SDK.
```python theme={null}
class SdkPluginConfig(TypedDict):
type: Literal["local"]
path: str
| Field | Type | Description |
|---|---|---|
type |
Literal["local"] |
Must be "local" (only local plugins currently supported) |
path |
str |
Absolute or relative path to the plugin directory |
Example:
```python theme={null} plugins = [ {"type": "local", "path": "./my-plugin"}, {"type": "local", "path": "/absolute/path/to/plugin"}, ]
For complete information on creating and using plugins, see [Plugins](https://code.claude.com/en/agent-sdk/plugins).
## Message Types
### `Message`
Union type of all possible messages.
```python theme={null}
Message = (
UserMessage
| AssistantMessage
| SystemMessage
| ResultMessage
| StreamEvent
| RateLimitEvent
)
UserMessage
User input message.
```python theme={null} @dataclass class UserMessage: content: str | list[ContentBlock] uuid: str | None = None parent_tool_use_id: str | None = None tool_use_result: dict[str, Any] | None = None
| Field | Type | Description |
| :------------------- | :-------------------------- | :---------------------------------------------------- |
| `content` | `str \| list[ContentBlock]` | Message content as text or content blocks |
| `uuid` | `str \| None` | Unique message identifier |
| `parent_tool_use_id` | `str \| None` | Tool use ID if this message is a tool result response |
| `tool_use_result` | `dict[str, Any] \| None` | Tool result data if applicable |
### `AssistantMessage`
Assistant response message with content blocks.
```python theme={null}
@dataclass
class AssistantMessage:
content: list[ContentBlock]
model: str
parent_tool_use_id: str | None = None
error: AssistantMessageError | None = None
usage: dict[str, Any] | None = None
message_id: str | None = None
| Field | Type | Description |
|---|---|---|
content |
list[ContentBlock] |
List of content blocks in the response |
model |
str |
Model that generated the response |
parent_tool_use_id |
str \| None |
Tool use ID if this is a nested response |
error |
AssistantMessageError \| None |
Error type if the response encountered an error |
usage |
dict[str, Any] \| None |
Per-message token usage (same keys as ResultMessage.usage) |
message_id |
str \| None |
API message ID. Multiple messages from one turn share the same ID |
AssistantMessageError
Possible error types for assistant messages.
```python theme={null} AssistantMessageError = Literal[ "authentication_failed", "billing_error", "rate_limit", "invalid_request", "server_error", "max_output_tokens", "unknown", ]
### `SystemMessage`
System message with metadata.
```python theme={null}
@dataclass
class SystemMessage:
subtype: str
data: dict[str, Any]
ResultMessage
Final result message with cost and usage information.
```python theme={null} @dataclass class ResultMessage: subtype: str duration_ms: int duration_api_ms: int is_error: bool num_turns: int session_id: str total_cost_usd: float | None = None usage: dict[str, Any] | None = None result: str | None = None stop_reason: str | None = None structured_output: Any = None model_usage: dict[str, Any] | None = None
The `usage` dict contains the following keys when present:
| Key | Type | Description |
| ----------------------------- | ----- | ---------------------------------------- |
| `input_tokens` | `int` | Total input tokens consumed. |
| `output_tokens` | `int` | Total output tokens generated. |
| `cache_creation_input_tokens` | `int` | Tokens used to create new cache entries. |
| `cache_read_input_tokens` | `int` | Tokens read from existing cache entries. |
The `model_usage` dict maps model names to per-model usage. The inner dict keys use camelCase because the value is passed through unmodified from the underlying CLI process, matching the TypeScript [`ModelUsage`](https://code.claude.com/en/agent-sdk/typescript#model-usage) type:
| Key | Type | Description |
| -------------------------- | ------- | ---------------------------------------------------------------------------------------------------------------------------------------- |
| `inputTokens` | `int` | Input tokens for this model. |
| `outputTokens` | `int` | Output tokens for this model. |
| `cacheReadInputTokens` | `int` | Cache read tokens for this model. |
| `cacheCreationInputTokens` | `int` | Cache creation tokens for this model. |
| `webSearchRequests` | `int` | Web search requests made by this model. |
| `costUSD` | `float` | Estimated cost in USD for this model, computed client-side. See [Track cost and usage](https://code.claude.com/en/agent-sdk/cost-tracking) for billing caveats. |
| `contextWindow` | `int` | Context window size for this model. |
| `maxOutputTokens` | `int` | Maximum output token limit for this model. |
### `StreamEvent`
Stream event for partial message updates during streaming. Only received when `include_partial_messages=True` in `ClaudeAgentOptions`. Import via `from claude_agent_sdk.types import StreamEvent`.
```python theme={null}
@dataclass
class StreamEvent:
uuid: str
session_id: str
event: dict[str, Any] # The raw Claude API stream event
parent_tool_use_id: str | None = None
| Field | Type | Description |
|---|---|---|
uuid |
str |
Unique identifier for this event |
session_id |
str |
Session identifier |
event |
dict[str, Any] |
The raw Claude API stream event data |
parent_tool_use_id |
str \| None |
Parent tool use ID if this event is from a subagent |
RateLimitEvent
Emitted when rate limit status changes (for example, from "allowed" to "allowed_warning"). Use this to warn users before they hit a hard limit, or to back off when status is "rejected".
```python theme={null} @dataclass class RateLimitEvent: rate_limit_info: RateLimitInfo uuid: str session_id: str
| Field | Type | Description |
| :---------------- | :---------------------------------- | :----------------------- |
| `rate_limit_info` | [`RateLimitInfo`](#rate-limit-info) | Current rate limit state |
| `uuid` | `str` | Unique event identifier |
| `session_id` | `str` | Session identifier |
### `RateLimitInfo`
Rate limit state carried by [`RateLimitEvent`](#rate-limit-event).
```python theme={null}
RateLimitStatus = Literal["allowed", "allowed_warning", "rejected"]
RateLimitType = Literal[
"five_hour", "seven_day", "seven_day_opus", "seven_day_sonnet", "overage"
]
@dataclass
class RateLimitInfo:
status: RateLimitStatus
resets_at: int | None = None
rate_limit_type: RateLimitType | None = None
utilization: float | None = None
overage_status: RateLimitStatus | None = None
overage_resets_at: int | None = None
overage_disabled_reason: str | None = None
raw: dict[str, Any] = field(default_factory=dict)
| Field | Type | Description |
|---|---|---|
status |
RateLimitStatus |
Current status. "allowed_warning" means approaching the limit; "rejected" means the limit was hit |
resets_at |
int \| None |
Unix timestamp when the rate limit window resets |
rate_limit_type |
RateLimitType \| None |
Which rate limit window applies |
utilization |
float \| None |
Fraction of the rate limit consumed (0.0 to 1.0) |
overage_status |
RateLimitStatus \| None |
Status of pay-as-you-go overage usage, if applicable |
overage_resets_at |
int \| None |
Unix timestamp when the overage window resets |
overage_disabled_reason |
str \| None |
Why overage is unavailable, if status is "rejected" |
raw |
dict[str, Any] |
Full raw dict from the CLI, including fields not modeled above |
TaskStartedMessage
Emitted when a background task starts. A background task is anything tracked outside the main turn: a backgrounded Bash command, a Monitor watch, a subagent spawned via the Agent tool, or a remote agent. The task_type field tells you which. This naming is unrelated to the Task-to-Agent tool rename.
```python theme={null} @dataclass class TaskStartedMessage(SystemMessage): task_id: str description: str uuid: str session_id: str tool_use_id: str | None = None task_type: str | None = None
| Field | Type | Description |
| :------------ | :------------ | :-------------------------------------------------------------------------------------------------------------------------- |
| `task_id` | `str` | Unique identifier for the task |
| `description` | `str` | Description of the task |
| `uuid` | `str` | Unique message identifier |
| `session_id` | `str` | Session identifier |
| `tool_use_id` | `str \| None` | Associated tool use ID |
| `task_type` | `str \| None` | Which kind of background task: `"local_bash"` for background Bash and Monitor watches, `"local_agent"`, or `"remote_agent"` |
### `TaskUsage`
Token and timing data for a background task.
```python theme={null}
class TaskUsage(TypedDict):
total_tokens: int
tool_uses: int
duration_ms: int
TaskProgressMessage
Emitted periodically with progress updates for a running background task.
```python theme={null} @dataclass class TaskProgressMessage(SystemMessage): task_id: str description: str usage: TaskUsage uuid: str session_id: str tool_use_id: str | None = None last_tool_name: str | None = None
| Field | Type | Description |
| :--------------- | :------------ | :---------------------------------- |
| `task_id` | `str` | Unique identifier for the task |
| `description` | `str` | Current status description |
| `usage` | `TaskUsage` | Token usage for this task so far |
| `uuid` | `str` | Unique message identifier |
| `session_id` | `str` | Session identifier |
| `tool_use_id` | `str \| None` | Associated tool use ID |
| `last_tool_name` | `str \| None` | Name of the last tool the task used |
### `TaskNotificationMessage`
Emitted when a background task completes, fails, or is stopped. Background tasks include `run_in_background` Bash commands, Monitor watches, and background subagents.
```python theme={null}
@dataclass
class TaskNotificationMessage(SystemMessage):
task_id: str
status: TaskNotificationStatus # "completed" | "failed" | "stopped"
output_file: str
summary: str
uuid: str
session_id: str
tool_use_id: str | None = None
usage: TaskUsage | None = None
| Field | Type | Description |
|---|---|---|
task_id |
str |
Unique identifier for the task |
status |
TaskNotificationStatus |
One of "completed", "failed", or "stopped" |
output_file |
str |
Path to the task output file |
summary |
str |
Summary of the task result |
uuid |
str |
Unique message identifier |
session_id |
str |
Session identifier |
tool_use_id |
str \| None |
Associated tool use ID |
usage |
TaskUsage \| None |
Final token usage for the task |
Content Block Types
ContentBlock
Union type of all content blocks.
```python theme={null} ContentBlock = TextBlock | ThinkingBlock | ToolUseBlock | ToolResultBlock
### `TextBlock`
Text content block.
```python theme={null}
@dataclass
class TextBlock:
text: str
ThinkingBlock
Thinking content block (for models with thinking capability).
```python theme={null} @dataclass class ThinkingBlock: thinking: str signature: str
### `ToolUseBlock`
Tool use request block.
```python theme={null}
@dataclass
class ToolUseBlock:
id: str
name: str
input: dict[str, Any]
ToolResultBlock
Tool execution result block.
```python theme={null} @dataclass class ToolResultBlock: tool_use_id: str content: str | list[dict[str, Any]] | None = None is_error: bool | None = None
## Error Types
### `ClaudeSDKError`
Base exception class for all SDK errors.
```python theme={null}
class ClaudeSDKError(Exception):
"""Base error for Claude SDK."""
CLINotFoundError
Raised when Claude Code CLI is not installed or not found.
```python theme={null} class CLINotFoundError(CLIConnectionError): def init( self, message: str = "Claude Code not found", cli_path: str | None = None ): """ Args: message: Error message (default: "Claude Code not found") cli_path: Optional path to the CLI that was not found """
### `CLIConnectionError`
Raised when connection to Claude Code fails.
```python theme={null}
class CLIConnectionError(ClaudeSDKError):
"""Failed to connect to Claude Code."""
ProcessError
Raised when the Claude Code process fails.
```python theme={null} class ProcessError(ClaudeSDKError): def init( self, message: str, exit_code: int | None = None, stderr: str | None = None ): self.exit_code = exit_code self.stderr = stderr
### `CLIJSONDecodeError`
Raised when JSON parsing fails.
```python theme={null}
class CLIJSONDecodeError(ClaudeSDKError):
def __init__(self, line: str, original_error: Exception):
"""
Args:
line: The line that failed to parse
original_error: The original JSON decode exception
"""
self.line = line
self.original_error = original_error
Hook Types
For a comprehensive guide on using hooks with examples and common patterns, see the Hooks guide.
HookEvent
Supported hook event types.
```python theme={null} HookEvent = Literal[ "PreToolUse", # Called before tool execution "PostToolUse", # Called after tool execution "PostToolUseFailure", # Called when a tool execution fails "UserPromptSubmit", # Called when user submits a prompt "Stop", # Called when stopping execution "SubagentStop", # Called when a subagent stops "PreCompact", # Called before message compaction "Notification", # Called for notification events "SubagentStart", # Called when a subagent starts "PermissionRequest", # Called when a permission decision is needed ]
<Note>
The TypeScript SDK supports additional hook events not yet available in Python: `SessionStart`, `SessionEnd`, `Setup`, `TeammateIdle`, `TaskCompleted`, `ConfigChange`, `WorktreeCreate`, and `WorktreeRemove`.
</Note>
### `HookCallback`
Type definition for hook callback functions.
```python theme={null}
HookCallback = Callable[[HookInput, str | None, HookContext], Awaitable[HookJSONOutput]]
Parameters:
input: Strongly-typed hook input with discriminated unions based onhook_event_name(seeHookInput)tool_use_id: Optional tool use identifier (for tool-related hooks)context: Hook context with additional information
Returns a HookJSONOutput that may contain:
decision:"block"to block the actionsystemMessage: System message to add to the transcripthookSpecificOutput: Hook-specific output data
HookContext
Context information passed to hook callbacks.
```python theme={null} class HookContext(TypedDict): signal: Any | None # Future: abort signal support
### `HookMatcher`
Configuration for matching hooks to specific events or tools.
```python theme={null}
@dataclass
class HookMatcher:
matcher: str | None = (
None # Tool name or pattern to match (e.g., "Bash", "Write|Edit")
)
hooks: list[HookCallback] = field(
default_factory=list
) # List of callbacks to execute
timeout: float | None = (
None # Timeout in seconds for all hooks in this matcher (default: 60)
)
HookInput
Union type of all hook input types. The actual type depends on the hook_event_name field.
```python theme={null} HookInput = ( PreToolUseHookInput | PostToolUseHookInput | PostToolUseFailureHookInput | UserPromptSubmitHookInput | StopHookInput | SubagentStopHookInput | PreCompactHookInput | NotificationHookInput | SubagentStartHookInput | PermissionRequestHookInput )
### `BaseHookInput`
Base fields present in all hook input types.
```python theme={null}
class BaseHookInput(TypedDict):
session_id: str
transcript_path: str
cwd: str
permission_mode: NotRequired[str]
| Field | Type | Description |
|---|---|---|
session_id |
str |
Current session identifier |
transcript_path |
str |
Path to the session transcript file |
cwd |
str |
Current working directory |
permission_mode |
str (optional) |
Current permission mode |
PreToolUseHookInput
Input data for PreToolUse hook events.
```python theme={null} class PreToolUseHookInput(BaseHookInput): hook_event_name: Literal["PreToolUse"] tool_name: str tool_input: dict[str, Any] tool_use_id: str agent_id: NotRequired[str] agent_type: NotRequired[str]
| Field | Type | Description |
| :---------------- | :---------------------- | :----------------------------------------------------------------- |
| `hook_event_name` | `Literal["PreToolUse"]` | Always "PreToolUse" |
| `tool_name` | `str` | Name of the tool about to be executed |
| `tool_input` | `dict[str, Any]` | Input parameters for the tool |
| `tool_use_id` | `str` | Unique identifier for this tool use |
| `agent_id` | `str` (optional) | Subagent identifier, present when the hook fires inside a subagent |
| `agent_type` | `str` (optional) | Subagent type, present when the hook fires inside a subagent |
### `PostToolUseHookInput`
Input data for `PostToolUse` hook events.
```python theme={null}
class PostToolUseHookInput(BaseHookInput):
hook_event_name: Literal["PostToolUse"]
tool_name: str
tool_input: dict[str, Any]
tool_response: Any
tool_use_id: str
agent_id: NotRequired[str]
agent_type: NotRequired[str]
| Field | Type | Description |
|---|---|---|
hook_event_name |
Literal["PostToolUse"] |
Always "PostToolUse" |
tool_name |
str |
Name of the tool that was executed |
tool_input |
dict[str, Any] |
Input parameters that were used |
tool_response |
Any |
Response from the tool execution |
tool_use_id |
str |
Unique identifier for this tool use |
agent_id |
str (optional) |
Subagent identifier, present when the hook fires inside a subagent |
agent_type |
str (optional) |
Subagent type, present when the hook fires inside a subagent |
PostToolUseFailureHookInput
Input data for PostToolUseFailure hook events. Called when a tool execution fails.
```python theme={null} class PostToolUseFailureHookInput(BaseHookInput): hook_event_name: Literal["PostToolUseFailure"] tool_name: str tool_input: dict[str, Any] tool_use_id: str error: str is_interrupt: NotRequired[bool] agent_id: NotRequired[str] agent_type: NotRequired[str]
| Field | Type | Description |
| :---------------- | :------------------------------ | :----------------------------------------------------------------- |
| `hook_event_name` | `Literal["PostToolUseFailure"]` | Always "PostToolUseFailure" |
| `tool_name` | `str` | Name of the tool that failed |
| `tool_input` | `dict[str, Any]` | Input parameters that were used |
| `tool_use_id` | `str` | Unique identifier for this tool use |
| `error` | `str` | Error message from the failed execution |
| `is_interrupt` | `bool` (optional) | Whether the failure was caused by an interrupt |
| `agent_id` | `str` (optional) | Subagent identifier, present when the hook fires inside a subagent |
| `agent_type` | `str` (optional) | Subagent type, present when the hook fires inside a subagent |
### `UserPromptSubmitHookInput`
Input data for `UserPromptSubmit` hook events.
```python theme={null}
class UserPromptSubmitHookInput(BaseHookInput):
hook_event_name: Literal["UserPromptSubmit"]
prompt: str
| Field | Type | Description |
|---|---|---|
hook_event_name |
Literal["UserPromptSubmit"] |
Always "UserPromptSubmit" |
prompt |
str |
The user's submitted prompt |
StopHookInput
Input data for Stop hook events.
```python theme={null} class StopHookInput(BaseHookInput): hook_event_name: Literal["Stop"] stop_hook_active: bool
| Field | Type | Description |
| :----------------- | :---------------- | :------------------------------ |
| `hook_event_name` | `Literal["Stop"]` | Always "Stop" |
| `stop_hook_active` | `bool` | Whether the stop hook is active |
### `SubagentStopHookInput`
Input data for `SubagentStop` hook events.
```python theme={null}
class SubagentStopHookInput(BaseHookInput):
hook_event_name: Literal["SubagentStop"]
stop_hook_active: bool
agent_id: str
agent_transcript_path: str
agent_type: str
| Field | Type | Description |
|---|---|---|
hook_event_name |
Literal["SubagentStop"] |
Always "SubagentStop" |
stop_hook_active |
bool |
Whether the stop hook is active |
agent_id |
str |
Unique identifier for the subagent |
agent_transcript_path |
str |
Path to the subagent's transcript file |
agent_type |
str |
Type of the subagent |
PreCompactHookInput
Input data for PreCompact hook events.
```python theme={null} class PreCompactHookInput(BaseHookInput): hook_event_name: Literal["PreCompact"] trigger: Literal["manual", "auto"] custom_instructions: str | None
| Field | Type | Description |
| :-------------------- | :-------------------------- | :--------------------------------- |
| `hook_event_name` | `Literal["PreCompact"]` | Always "PreCompact" |
| `trigger` | `Literal["manual", "auto"]` | What triggered the compaction |
| `custom_instructions` | `str \| None` | Custom instructions for compaction |
### `NotificationHookInput`
Input data for `Notification` hook events.
```python theme={null}
class NotificationHookInput(BaseHookInput):
hook_event_name: Literal["Notification"]
message: str
title: NotRequired[str]
notification_type: str
| Field | Type | Description |
|---|---|---|
hook_event_name |
Literal["Notification"] |
Always "Notification" |
message |
str |
Notification message content |
title |
str (optional) |
Notification title |
notification_type |
str |
Type of notification |
SubagentStartHookInput
Input data for SubagentStart hook events.
```python theme={null} class SubagentStartHookInput(BaseHookInput): hook_event_name: Literal["SubagentStart"] agent_id: str agent_type: str
| Field | Type | Description |
| :---------------- | :------------------------- | :--------------------------------- |
| `hook_event_name` | `Literal["SubagentStart"]` | Always "SubagentStart" |
| `agent_id` | `str` | Unique identifier for the subagent |
| `agent_type` | `str` | Type of the subagent |
### `PermissionRequestHookInput`
Input data for `PermissionRequest` hook events. Allows hooks to handle permission decisions programmatically.
```python theme={null}
class PermissionRequestHookInput(BaseHookInput):
hook_event_name: Literal["PermissionRequest"]
tool_name: str
tool_input: dict[str, Any]
permission_suggestions: NotRequired[list[Any]]
| Field | Type | Description |
|---|---|---|
hook_event_name |
Literal["PermissionRequest"] |
Always "PermissionRequest" |
tool_name |
str |
Name of the tool requesting permission |
tool_input |
dict[str, Any] |
Input parameters for the tool |
permission_suggestions |
list[Any] (optional) |
Suggested permission updates from the CLI |
HookJSONOutput
Union type for hook callback return values.
```python theme={null} HookJSONOutput = AsyncHookJSONOutput | SyncHookJSONOutput
#### `SyncHookJSONOutput`
Synchronous hook output with control and decision fields.
```python theme={null}
class SyncHookJSONOutput(TypedDict):
# Control fields
continue_: NotRequired[bool] # Whether to proceed (default: True)
suppressOutput: NotRequired[bool] # Hide stdout from transcript
stopReason: NotRequired[str] # Message when continue is False
# Decision fields
decision: NotRequired[Literal["block"]]
systemMessage: NotRequired[str] # Warning message for user
reason: NotRequired[str] # Feedback for Claude
# Hook-specific output
hookSpecificOutput: NotRequired[HookSpecificOutput]
continue_ (with underscore) in Python code. It is automatically converted to continue when sent to the CLI.
HookSpecificOutput
A TypedDict containing the hook event name and event-specific fields. The shape depends on the hookEventName value. For full details on available fields per hook event, see Control execution with hooks.
A discriminated union of event-specific output types. The hookEventName field determines which fields are valid.
```python theme={null} class PreToolUseHookSpecificOutput(TypedDict): hookEventName: Literal["PreToolUse"] permissionDecision: NotRequired[Literal["allow", "deny", "ask"]] permissionDecisionReason: NotRequired[str] updatedInput: NotRequired[dict[str, Any]] additionalContext: NotRequired[str]
class PostToolUseHookSpecificOutput(TypedDict): hookEventName: Literal["PostToolUse"] additionalContext: NotRequired[str] updatedMCPToolOutput: NotRequired[Any]
class PostToolUseFailureHookSpecificOutput(TypedDict): hookEventName: Literal["PostToolUseFailure"] additionalContext: NotRequired[str]
class UserPromptSubmitHookSpecificOutput(TypedDict): hookEventName: Literal["UserPromptSubmit"] additionalContext: NotRequired[str]
class NotificationHookSpecificOutput(TypedDict): hookEventName: Literal["Notification"] additionalContext: NotRequired[str]
class SubagentStartHookSpecificOutput(TypedDict): hookEventName: Literal["SubagentStart"] additionalContext: NotRequired[str]
class PermissionRequestHookSpecificOutput(TypedDict): hookEventName: Literal["PermissionRequest"] decision: dict[str, Any]
HookSpecificOutput = ( PreToolUseHookSpecificOutput | PostToolUseHookSpecificOutput | PostToolUseFailureHookSpecificOutput | UserPromptSubmitHookSpecificOutput | NotificationHookSpecificOutput | SubagentStartHookSpecificOutput | PermissionRequestHookSpecificOutput )
#### `AsyncHookJSONOutput`
Async hook output that defers hook execution.
```python theme={null}
class AsyncHookJSONOutput(TypedDict):
async_: Literal[True] # Set to True to defer execution
asyncTimeout: NotRequired[int] # Timeout in milliseconds
async_ (with underscore) in Python code. It is automatically converted to async when sent to the CLI.
Hook Usage Example
This example registers two hooks: one that blocks dangerous bash commands like rm -rf /, and another that logs all tool usage for auditing. The security hook only runs on Bash commands (via the matcher), while the logging hook runs on all tools.
```python theme={null} from claude_agent_sdk import query, ClaudeAgentOptions, HookMatcher, HookContext from typing import Any
async def validate_bash_command( input_data: dict[str, Any], tool_use_id: str | None, context: HookContext ) -> dict[str, Any]: """Validate and potentially block dangerous bash commands.""" if input_data["tool_name"] == "Bash": command = input_data["tool_input"].get("command", "") if "rm -rf /" in command: return { "hookSpecificOutput": { "hookEventName": "PreToolUse", "permissionDecision": "deny", "permissionDecisionReason": "Dangerous command blocked", } } return {}
async def log_tool_use( input_data: dict[str, Any], tool_use_id: str | None, context: HookContext ) -> dict[str, Any]: """Log all tool usage for auditing.""" print(f"Tool used: {input_data.get('tool_name')}") return {}
options = ClaudeAgentOptions( hooks={ "PreToolUse": [ HookMatcher( matcher="Bash", hooks=[validate_bash_command], timeout=120 ), # 2 min for validation HookMatcher( hooks=[log_tool_use] ), # Applies to all tools (default 60s timeout) ], "PostToolUse": [HookMatcher(hooks=[log_tool_use])], } )
async for message in query(prompt="Analyze this codebase", options=options): print(message)
## Tool Input/Output Types
Documentation of input/output schemas for all built-in Claude Code tools. While the Python SDK doesn't export these as types, they represent the structure of tool inputs and outputs in messages.
### Agent
**Tool name:** `Agent` (previously `Task`, which is still accepted as an alias)
**Input:**
```python theme={null}
{
"description": str, # A short (3-5 word) description of the task
"prompt": str, # The task for the agent to perform
"subagent_type": str, # The type of specialized agent to use
}
Output:
```python theme={null} { "result": str, # Final result from the subagent "usage": dict | None, # Token usage statistics "total_cost_usd": float | None, # Estimated total cost in USD "duration_ms": int | None, # Execution duration in milliseconds }
### AskUserQuestion
**Tool name:** `AskUserQuestion`
Asks the user clarifying questions during execution. See [Handle approvals and user input](https://code.claude.com/en/agent-sdk/user-input#handle-clarifying-questions) for usage details.
**Input:**
```python theme={null}
{
"questions": [ # Questions to ask the user (1-4 questions)
{
"question": str, # The complete question to ask the user
"header": str, # Very short label displayed as a chip/tag (max 12 chars)
"options": [ # The available choices (2-4 options)
{
"label": str, # Display text for this option (1-5 words)
"description": str, # Explanation of what this option means
}
],
"multiSelect": bool, # Set to true to allow multiple selections
}
],
"answers": dict | None, # User answers populated by the permission system
}
Output:
```python theme={null} { "questions": [ # The questions that were asked { "question": str, "header": str, "options": [{"label": str, "description": str}], "multiSelect": bool, } ], "answers": dict[str, str], # Maps question text to answer string # Multi-select answers are comma-separated }
### Bash
**Tool name:** `Bash`
**Input:**
```python theme={null}
{
"command": str, # The command to execute
"timeout": int | None, # Optional timeout in milliseconds (max 600000)
"description": str | None, # Clear, concise description (5-10 words)
"run_in_background": bool | None, # Set to true to run in background
}
Output:
```python theme={null} { "output": str, # Combined stdout and stderr output "exitCode": int, # Exit code of the command "killed": bool | None, # Whether command was killed due to timeout "shellId": str | None, # Shell ID for background processes }
### Monitor
**Tool name:** `Monitor`
Runs a background script and delivers each stdout line to Claude as an event so it can react without polling. Monitor follows the same permission rules as Bash. See the [Monitor tool reference](https://code.claude.com/en/tools-reference#monitor-tool) for behavior and provider availability.
**Input:**
```python theme={null}
{
"command": str, # Shell script; each stdout line is an event, exit ends the watch
"description": str, # Short description shown in notifications
"timeout_ms": int | None, # Kill after this deadline (default 300000, max 3600000)
"persistent": bool | None, # Run for the lifetime of the session; stop with TaskStop
}
Output:
```python theme={null} { "taskId": str, # ID of the background monitor task "timeoutMs": int, # Timeout deadline in milliseconds (0 when persistent) "persistent": bool | None, # True when running until TaskStop or session end }
### Edit
**Tool name:** `Edit`
**Input:**
```python theme={null}
{
"file_path": str, # The absolute path to the file to modify
"old_string": str, # The text to replace
"new_string": str, # The text to replace it with
"replace_all": bool | None, # Replace all occurrences (default False)
}
Output:
```python theme={null} { "message": str, # Confirmation message "replacements": int, # Number of replacements made "file_path": str, # File path that was edited }
### Read
**Tool name:** `Read`
**Input:**
```python theme={null}
{
"file_path": str, # The absolute path to the file to read
"offset": int | None, # The line number to start reading from
"limit": int | None, # The number of lines to read
}
Output (Text files):
```python theme={null} { "content": str, # File contents with line numbers "total_lines": int, # Total number of lines in file "lines_returned": int, # Lines actually returned }
**Output (Images):**
```python theme={null}
{
"image": str, # Base64 encoded image data
"mime_type": str, # Image MIME type
"file_size": int, # File size in bytes
}
Write
Tool name: Write
Input:
```python theme={null} { "file_path": str, # The absolute path to the file to write "content": str, # The content to write to the file }
**Output:**
```python theme={null}
{
"message": str, # Success message
"bytes_written": int, # Number of bytes written
"file_path": str, # File path that was written
}
Glob
Tool name: Glob
Input:
```python theme={null} { "pattern": str, # The glob pattern to match files against "path": str | None, # The directory to search in (defaults to cwd) }
**Output:**
```python theme={null}
{
"matches": list[str], # Array of matching file paths
"count": int, # Number of matches found
"search_path": str, # Search directory used
}
Grep
Tool name: Grep
Input:
```python theme={null} { "pattern": str, # The regular expression pattern "path": str | None, # File or directory to search in "glob": str | None, # Glob pattern to filter files "type": str | None, # File type to search "output_mode": str | None, # "content", "files_with_matches", or "count" "-i": bool | None, # Case insensitive search "-n": bool | None, # Show line numbers "-B": int | None, # Lines to show before each match "-A": int | None, # Lines to show after each match "-C": int | None, # Lines to show before and after "head_limit": int | None, # Limit output to first N lines/entries "multiline": bool | None, # Enable multiline mode }
**Output (content mode):**
```python theme={null}
{
"matches": [
{
"file": str,
"line_number": int | None,
"line": str,
"before_context": list[str] | None,
"after_context": list[str] | None,
}
],
"total_matches": int,
}
Output (files_with_matches mode):
```python theme={null} { "files": list[str], # Files containing matches "count": int, # Number of files with matches }
### NotebookEdit
**Tool name:** `NotebookEdit`
**Input:**
```python theme={null}
{
"notebook_path": str, # Absolute path to the Jupyter notebook
"cell_id": str | None, # The ID of the cell to edit
"new_source": str, # The new source for the cell
"cell_type": "code" | "markdown" | None, # The type of the cell
"edit_mode": "replace" | "insert" | "delete" | None, # Edit operation type
}
Output:
```python theme={null} { "message": str, # Success message "edit_type": "replaced" | "inserted" | "deleted", # Type of edit performed "cell_id": str | None, # Cell ID that was affected "total_cells": int, # Total cells in notebook after edit }
### WebFetch
**Tool name:** `WebFetch`
**Input:**
```python theme={null}
{
"url": str, # The URL to fetch content from
"prompt": str, # The prompt to run on the fetched content
}
Output:
```python theme={null} { "response": str, # AI model's response to the prompt "url": str, # URL that was fetched "final_url": str | None, # Final URL after redirects "status_code": int | None, # HTTP status code }
### WebSearch
**Tool name:** `WebSearch`
**Input:**
```python theme={null}
{
"query": str, # The search query to use
"allowed_domains": list[str] | None, # Only include results from these domains
"blocked_domains": list[str] | None, # Never include results from these domains
}
Output:
```python theme={null} { "results": [{"title": str, "url": str, "snippet": str, "metadata": dict | None}], "total_results": int, "query": str, }
### TodoWrite
**Tool name:** `TodoWrite`
**Input:**
```python theme={null}
{
"todos": [
{
"content": str, # The task description
"status": "pending" | "in_progress" | "completed", # Task status
"activeForm": str, # Active form of the description
}
]
}
Output:
```python theme={null} { "message": str, # Success message "stats": {"total": int, "pending": int, "in_progress": int, "completed": int}, }
### BashOutput
**Tool name:** `BashOutput`
**Input:**
```python theme={null}
{
"bash_id": str, # The ID of the background shell
"filter": str | None, # Optional regex to filter output lines
}
Output:
```python theme={null} { "output": str, # New output since last check "status": "running" | "completed" | "failed", # Current shell status "exitCode": int | None, # Exit code when completed }
### KillBash
**Tool name:** `KillBash`
**Input:**
```python theme={null}
{
"shell_id": str # The ID of the background shell to kill
}
Output:
```python theme={null} { "message": str, # Success message "shell_id": str, # ID of the killed shell }
### ExitPlanMode
**Tool name:** `ExitPlanMode`
**Input:**
```python theme={null}
{
"plan": str # The plan to run by the user for approval
}
Output:
```python theme={null} { "message": str, # Confirmation message "approved": bool | None, # Whether user approved the plan }
### ListMcpResources
**Tool name:** `ListMcpResources`
**Input:**
```python theme={null}
{
"server": str | None # Optional server name to filter resources by
}
Output:
```python theme={null} { "resources": [ { "uri": str, "name": str, "description": str | None, "mimeType": str | None, "server": str, } ], "total": int, }
### ReadMcpResource
**Tool name:** `ReadMcpResource`
**Input:**
```python theme={null}
{
"server": str, # The MCP server name
"uri": str, # The resource URI to read
}
Output:
```python theme={null} { "contents": [ {"uri": str, "mimeType": str | None, "text": str | None, "blob": str | None} ], "server": str, }
## Advanced Features with ClaudeSDKClient
### Building a Continuous Conversation Interface
```python theme={null}
from claude_agent_sdk import (
ClaudeSDKClient,
ClaudeAgentOptions,
AssistantMessage,
TextBlock,
)
import asyncio
class ConversationSession:
"""Maintains a single conversation session with Claude."""
def __init__(self, options: ClaudeAgentOptions | None = None):
self.client = ClaudeSDKClient(options)
self.turn_count = 0
async def start(self):
await self.client.connect()
print("Starting conversation session. Claude will remember context.")
print(
"Commands: 'exit' to quit, 'interrupt' to stop current task, 'new' for new session"
)
while True:
user_input = input(f"\n[Turn {self.turn_count + 1}] You: ")
if user_input.lower() == "exit":
break
elif user_input.lower() == "interrupt":
await self.client.interrupt()
print("Task interrupted!")
continue
elif user_input.lower() == "new":
# Disconnect and reconnect for a fresh session
await self.client.disconnect()
await self.client.connect()
self.turn_count = 0
print("Started new conversation session (previous context cleared)")
continue
# Send message - the session retains all previous messages
await self.client.query(user_input)
self.turn_count += 1
# Process response
print(f"[Turn {self.turn_count}] Claude: ", end="")
async for message in self.client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(block.text, end="")
print() # New line after response
await self.client.disconnect()
print(f"Conversation ended after {self.turn_count} turns.")
async def main():
options = ClaudeAgentOptions(
allowed_tools=["Read", "Write", "Bash"], permission_mode="acceptEdits"
)
session = ConversationSession(options)
await session.start()
# Example conversation:
# Turn 1 - You: "Create a file called hello.py"
# Turn 1 - Claude: "I'll create a hello.py file for you..."
# Turn 2 - You: "What's in that file?"
# Turn 2 - Claude: "The hello.py file I just created contains..." (remembers!)
# Turn 3 - You: "Add a main function to it"
# Turn 3 - Claude: "I'll add a main function to hello.py..." (knows which file!)
asyncio.run(main())
Using Hooks for Behavior Modification
```python theme={null} from claude_agent_sdk import ( ClaudeSDKClient, ClaudeAgentOptions, HookMatcher, HookContext, ) import asyncio from typing import Any
async def pre_tool_logger( input_data: dict[str, Any], tool_use_id: str | None, context: HookContext ) -> dict[str, Any]: """Log all tool usage before execution.""" tool_name = input_data.get("tool_name", "unknown") print(f"[PRE-TOOL] About to use: {tool_name}")
# You can modify or block the tool execution here
if tool_name == "Bash" and "rm -rf" in str(input_data.get("tool_input", {})):
return {
"hookSpecificOutput": {
"hookEventName": "PreToolUse",
"permissionDecision": "deny",
"permissionDecisionReason": "Dangerous command blocked",
}
}
return {}
async def post_tool_logger( input_data: dict[str, Any], tool_use_id: str | None, context: HookContext ) -> dict[str, Any]: """Log results after tool execution.""" tool_name = input_data.get("tool_name", "unknown") print(f"[POST-TOOL] Completed: {tool_name}") return {}
async def user_prompt_modifier( input_data: dict[str, Any], tool_use_id: str | None, context: HookContext ) -> dict[str, Any]: """Add context to user prompts.""" original_prompt = input_data.get("prompt", "")
# Add a timestamp as additional context for Claude to see
from datetime import datetime
timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
return {
"hookSpecificOutput": {
"hookEventName": "UserPromptSubmit",
"additionalContext": f"[Submitted at {timestamp}] Original prompt: {original_prompt}",
}
}
async def main(): options = ClaudeAgentOptions( hooks={ "PreToolUse": [ HookMatcher(hooks=[pre_tool_logger]), HookMatcher(matcher="Bash", hooks=[pre_tool_logger]), ], "PostToolUse": [HookMatcher(hooks=[post_tool_logger])], "UserPromptSubmit": [HookMatcher(hooks=[user_prompt_modifier])], }, allowed_tools=["Read", "Write", "Bash"], )
async with ClaudeSDKClient(options=options) as client:
await client.query("List files in current directory")
async for message in client.receive_response():
# Hooks will automatically log tool usage
pass
asyncio.run(main())
### Real-time Progress Monitoring
```python theme={null}
from claude_agent_sdk import (
ClaudeSDKClient,
ClaudeAgentOptions,
AssistantMessage,
ToolUseBlock,
ToolResultBlock,
TextBlock,
)
import asyncio
async def monitor_progress():
options = ClaudeAgentOptions(
allowed_tools=["Write", "Bash"], permission_mode="acceptEdits"
)
async with ClaudeSDKClient(options=options) as client:
await client.query("Create 5 Python files with different sorting algorithms")
# Monitor progress in real-time
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, ToolUseBlock):
if block.name == "Write":
file_path = block.input.get("file_path", "")
print(f"Creating: {file_path}")
elif isinstance(block, ToolResultBlock):
print("Completed tool execution")
elif isinstance(block, TextBlock):
print(f"Claude says: {block.text[:100]}...")
print("Task completed!")
asyncio.run(monitor_progress())
Example Usage
Basic file operations (using query)
```python theme={null} from claude_agent_sdk import query, ClaudeAgentOptions, AssistantMessage, ToolUseBlock import asyncio
async def create_project(): options = ClaudeAgentOptions( allowed_tools=["Read", "Write", "Bash"], permission_mode="acceptEdits", cwd="/home/user/project", )
async for message in query(
prompt="Create a Python project structure with setup.py", options=options
):
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, ToolUseBlock):
print(f"Using tool: {block.name}")
asyncio.run(create_project())
### Error handling
```python theme={null}
from claude_agent_sdk import query, CLINotFoundError, ProcessError, CLIJSONDecodeError
try:
async for message in query(prompt="Hello"):
print(message)
except CLINotFoundError:
print(
"Claude Code CLI not found. Try reinstalling: pip install --force-reinstall claude-agent-sdk"
)
except ProcessError as e:
print(f"Process failed with exit code: {e.exit_code}")
except CLIJSONDecodeError as e:
print(f"Failed to parse response: {e}")
Streaming mode with client
```python theme={null} from claude_agent_sdk import ClaudeSDKClient import asyncio
async def interactive_session(): async with ClaudeSDKClient() as client: # Send initial message await client.query("What's the weather like?")
# Process responses
async for msg in client.receive_response():
print(msg)
# Send follow-up
await client.query("Tell me more about that")
# Process follow-up response
async for msg in client.receive_response():
print(msg)
asyncio.run(interactive_session())
### Using custom tools with ClaudeSDKClient
```python theme={null}
from claude_agent_sdk import (
ClaudeSDKClient,
ClaudeAgentOptions,
tool,
create_sdk_mcp_server,
AssistantMessage,
TextBlock,
)
import asyncio
from typing import Any
# Define custom tools with @tool decorator
@tool("calculate", "Perform mathematical calculations", {"expression": str})
async def calculate(args: dict[str, Any]) -> dict[str, Any]:
try:
result = eval(args["expression"], {"__builtins__": {}})
return {"content": [{"type": "text", "text": f"Result: {result}"}]}
except Exception as e:
return {
"content": [{"type": "text", "text": f"Error: {str(e)}"}],
"is_error": True,
}
@tool("get_time", "Get current time", {})
async def get_time(args: dict[str, Any]) -> dict[str, Any]:
from datetime import datetime
current_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
return {"content": [{"type": "text", "text": f"Current time: {current_time}"}]}
async def main():
# Create SDK MCP server with custom tools
my_server = create_sdk_mcp_server(
name="utilities", version="1.0.0", tools=[calculate, get_time]
)
# Configure options with the server
options = ClaudeAgentOptions(
mcp_servers={"utils": my_server},
allowed_tools=["mcp__utils__calculate", "mcp__utils__get_time"],
)
# Use ClaudeSDKClient for interactive tool usage
async with ClaudeSDKClient(options=options) as client:
await client.query("What's 123 * 456?")
# Process calculation response
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Calculation: {block.text}")
# Follow up with time query
await client.query("What time is it now?")
async for message in client.receive_response():
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Time: {block.text}")
asyncio.run(main())
Sandbox Configuration
SandboxSettings
Configuration for sandbox behavior. Use this to enable command sandboxing and configure network restrictions programmatically.
```python theme={null} class SandboxSettings(TypedDict, total=False): enabled: bool autoAllowBashIfSandboxed: bool excludedCommands: list[str] allowUnsandboxedCommands: bool network: SandboxNetworkConfig ignoreViolations: SandboxIgnoreViolations enableWeakerNestedSandbox: bool
| Property | Type | Default | Description |
| :-------------------------- | :------------------------------------------------------ | :------ | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `enabled` | `bool` | `False` | Enable sandbox mode for command execution |
| `autoAllowBashIfSandboxed` | `bool` | `True` | Auto-approve bash commands when sandbox is enabled |
| `excludedCommands` | `list[str]` | `[]` | Commands that always bypass sandbox restrictions (e.g., `["docker"]`). These run unsandboxed automatically without model involvement |
| `allowUnsandboxedCommands` | `bool` | `True` | Allow the model to request running commands outside the sandbox. When `True`, the model can set `dangerouslyDisableSandbox` in tool input, which falls back to the [permissions system](#permissions-fallback-for-unsandboxed-commands) |
| `network` | [`SandboxNetworkConfig`](#sandbox-network-config) | `None` | Network-specific sandbox configuration |
| `ignoreViolations` | [`SandboxIgnoreViolations`](#sandbox-ignore-violations) | `None` | Configure which sandbox violations to ignore |
| `enableWeakerNestedSandbox` | `bool` | `False` | Enable a weaker nested sandbox for compatibility |
<Note>
**Filesystem and network access restrictions** are NOT configured via sandbox settings. Instead, they are derived from [permission rules](https://code.claude.com/en/settings#permission-settings):
* **Filesystem read restrictions**: Read deny rules
* **Filesystem write restrictions**: Edit allow/deny rules
* **Network restrictions**: WebFetch allow/deny rules
Use sandbox settings for command execution sandboxing, and permission rules for filesystem and network access control.
</Note>
#### Example usage
```python theme={null}
from claude_agent_sdk import query, ClaudeAgentOptions, SandboxSettings
sandbox_settings: SandboxSettings = {
"enabled": True,
"autoAllowBashIfSandboxed": True,
"network": {"allowLocalBinding": True},
}
async for message in query(
prompt="Build and test my project",
options=ClaudeAgentOptions(sandbox=sandbox_settings),
):
print(message)
allowUnixSockets option can grant access to powerful system services. For example, allowing /var/run/docker.sock effectively grants full host system access through the Docker API, bypassing sandbox isolation. Only allow Unix sockets that are strictly necessary and understand the security implications of each.
SandboxNetworkConfig
Network-specific configuration for sandbox mode.
```python theme={null} class SandboxNetworkConfig(TypedDict, total=False): allowLocalBinding: bool allowUnixSockets: list[str] allowAllUnixSockets: bool httpProxyPort: int socksProxyPort: int
| Property | Type | Default | Description |
| :-------------------- | :---------- | :------ | :---------------------------------------------------------------- |
| `allowLocalBinding` | `bool` | `False` | Allow processes to bind to local ports (e.g., for dev servers) |
| `allowUnixSockets` | `list[str]` | `[]` | Unix socket paths that processes can access (e.g., Docker socket) |
| `allowAllUnixSockets` | `bool` | `False` | Allow access to all Unix sockets |
| `httpProxyPort` | `int` | `None` | HTTP proxy port for network requests |
| `socksProxyPort` | `int` | `None` | SOCKS proxy port for network requests |
### `SandboxIgnoreViolations`
Configuration for ignoring specific sandbox violations.
```python theme={null}
class SandboxIgnoreViolations(TypedDict, total=False):
file: list[str]
network: list[str]
| Property | Type | Default | Description |
|---|---|---|---|
file |
list[str] |
[] |
File path patterns to ignore violations for |
network |
list[str] |
[] |
Network patterns to ignore violations for |
Permissions Fallback for Unsandboxed Commands
When allowUnsandboxedCommands is enabled, the model can request to run commands outside the sandbox by setting dangerouslyDisableSandbox: True in the tool input. These requests fall back to the existing permissions system, meaning your can_use_tool handler will be invoked, allowing you to implement custom authorization logic.
excludedCommands vs allowUnsandboxedCommands:
excludedCommands: A static list of commands that always bypass the sandbox automatically (e.g.,["docker"]). The model has no control over this.allowUnsandboxedCommands: Lets the model decide at runtime whether to request unsandboxed execution by settingdangerouslyDisableSandbox: Truein the tool input.
```python theme={null} from claude_agent_sdk import ( query, ClaudeAgentOptions, HookMatcher, PermissionResultAllow, PermissionResultDeny, ToolPermissionContext, )
async def can_use_tool( tool: str, input: dict, context: ToolPermissionContext ) -> PermissionResultAllow | PermissionResultDeny: # Check if the model is requesting to bypass the sandbox if tool == "Bash" and input.get("dangerouslyDisableSandbox"): # The model is requesting to run this command outside the sandbox print(f"Unsandboxed command requested: {input.get('command')}")
if is_command_authorized(input.get("command")):
return PermissionResultAllow()
return PermissionResultDeny(
message="Command not authorized for unsandboxed execution"
)
return PermissionResultAllow()
Required: dummy hook keeps the stream open for can_use_tool
async def dummy_hook(input_data, tool_use_id, context): return {"continue_": True}
async def prompt_stream(): yield { "type": "user", "message": {"role": "user", "content": "Deploy my application"}, }
async def main(): async for message in query( prompt=prompt_stream(), options=ClaudeAgentOptions( sandbox={ "enabled": True, "allowUnsandboxedCommands": True, # Model can request unsandboxed execution }, permission_mode="default", can_use_tool=can_use_tool, hooks={"PreToolUse": [HookMatcher(matcher=None, hooks=[dummy_hook])]}, ), ): print(message) ```
This pattern enables you to:
- Audit model requests: Log when the model requests unsandboxed execution
- Implement allowlists: Only permit specific commands to run unsandboxed
- Add approval workflows: Require explicit authorization for privileged operations
dangerouslyDisableSandbox: True have full system access. Ensure your can_use_tool handler validates these requests carefully.
If permission_mode is set to bypassPermissions and allow_unsandboxed_commands is enabled, the model can autonomously execute commands outside the sandbox without any approval prompts. This combination effectively allows the model to escape sandbox isolation silently.
See also
- SDK overview - General SDK concepts
- TypeScript SDK reference - TypeScript SDK documentation
- CLI reference - Command-line interface
- Common workflows - Step-by-step guides