hook-development

name

hook-development

description

[Utility] Guide for developing Claude Code hooks - shell commands that execute automatically in response to tool calls and notifications. Use this when users want to create, debug, or optimize hooks for automating workflows like linting, formatting, notifications, or custom validations. Supports PreToolUse, PostToolUse, Stop, SubagentStop, SessionStart, SessionEnd, UserPromptSubmit, PreCompact, Notification events.

Hook Development for Claude Code Plugins

Overview

Hooks are event-driven automation scripts that execute in response to Claude Code events. Use hooks to validate operations, enforce policies, add context, and integrate external tools into workflows.

Hook Types

Prompt-Based Hooks (Recommended)

Use LLM-driven decision making for context-aware validation.

Command Hooks

Execute bash commands for deterministic checks.

Hook Events

Event	When	Use For
PreToolUse	Before tool	Validation, modification
PostToolUse	After tool	Feedback, logging
UserPromptSubmit	User input	Context, validation
Stop	Agent stopping	Completeness check
SubagentStop	Subagent done	Task validation
SessionStart	Session begins	Context loading
SessionEnd	Session ends	Cleanup, logging
PreCompact	Before compact	Preserve context
Notification	User notified	Logging, reactions

Environment Variables

• $CLAUDE_PROJECT_DIR - Project root path
• $CLAUDE_PLUGIN_ROOT - Plugin directory
• $CLAUDE_ENV_FILE - SessionStart only: persist env vars here

Best Practices

• Use prompt-based hooks for complex logic
• Use ${CLAUDE_PLUGIN_ROOT} for portability
• Validate all inputs in command hooks
• Set appropriate timeouts