Skill System

Description

The Skill System provides reusable, composable workflows defined as markdown documents in src/skills/ and executed through the SkillTool. Skills are invoked via slash commands (e.g., /commit, /review-pr, /simplify) and inject structured instructions into the agent's context that guide multi-step task execution. Users can also define custom skills in their project or user configuration.

How Skills Work

A skill is a markdown file containing instructions, constraints, and optional tool-use patterns. When a user triggers a skill (either by typing a slash command or when the agent identifies a matching skill via the Skill tool), the system:

  1. Matches the user's request against available skill definitions using keyword and intent matching.
  2. Loads the matched skill's markdown content into the conversation as a <command-name> tagged instruction block.
  3. Executes the instructions within the current agent context, inheriting the session's permission-pipeline and memory-hierarchy.

The SkillTool is the tool-use interface that the model calls to invoke skills programmatically. It accepts a skill name and optional arguments, then injects the skill's instructions into the active conversation turn.

Built-in Skills

Skill Slash Command Purpose
Commit /commit Stage changes, generate commit message, create git commit
Review PR /review-pr Analyze pull request changes, provide structured feedback
Simplify /simplify Review changed code for reuse, quality, and efficiency
Loop /loop Run a prompt or slash command on a recurring interval
Schedule /schedule Create or manage scheduled remote agent triggers
Claude API /claude-api Help build apps using the Anthropic SDK
Update Config /update-config Configure settings.json for hooks and automated behaviors

Custom Skills

Users can define custom skills by placing markdown files in .claude/skills/ at the project level or ~/.claude/skills/ at the user level. A custom skill file follows the same format as built-in skills: a markdown document with a frontmatter block specifying the skill name, trigger patterns, and description. Custom skills appear alongside built-in skills in the slash command menu and can be invoked identically.

Integration

Skills frequently compose with other systems: the /commit skill uses the hooks-system to run pre-commit hooks, the /review-pr skill leverages grep-over-rag for codebase search, and scheduled skills run through the forked-agent-pattern for background execution. The bridge-system forwards skill invocations to IDE extensions, and the plugin-system can register additional skills.

Key claims

Relations

Sources

src-20260409-e7da1a492842