Claude Code Hooks — Automate Your AI Workflow

What are Claude Code Hooks?

Claude Code Hooks are automation triggers that run shell commands in response to Claude Code events. They let you enforce coding standards, run tests, validate changes, and integrate with external tools — all automatically, without Claude needing to remember to do it.

Answer-Ready: Claude Code Hooks are built-in automation triggers that run shell commands on events like file edits, tool calls, and notifications. Enforce linting, auto-testing, and custom validation in your Claude Code workflow.

Best for: Developers who want automated quality checks in their Claude Code workflow. Works with: Claude Code CLI and IDE extensions. Setup time: Under 2 minutes.

Core Features

1. Event Types

2. Tool Matchers

Target specific tools:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Edit|Write",
        "command": "prettier --write $CLAUDE_FILE_PATH"
      },
      {
        "matcher": "Bash",
        "command": "echo 'Command executed: $CLAUDE_TOOL_INPUT'"
      }
    ]
  }
}

3. Common Hook Patterns

Auto-lint on file changes:

{
  "matcher": "Edit|Write",
  "command": "eslint --fix $CLAUDE_FILE_PATH 2>/dev/null || true"
}

Run tests after code changes:

{
  "matcher": "Edit",
  "command": "npm test -- --related $CLAUDE_FILE_PATH 2>&1 | tail -5"
}

Type-check TypeScript files:

{
  "matcher": "Edit|Write",
  "command": "[[ $CLAUDE_FILE_PATH == *.ts ]] && npx tsc --noEmit 2>&1 | head -20 || true"
}

Block commits without tests:

{
  "matcher": "Bash",
  "command": "if echo $CLAUDE_TOOL_INPUT | grep -q 'git commit'; then npm test || exit 1; fi"
}

4. Environment Variables

5. Hook Output

Hook stdout is fed back to Claude as context:

{
  "matcher": "Edit",
  "command": "python check_style.py $CLAUDE_FILE_PATH"
}

If the style checker reports issues, Claude sees the output and can fix them.

Advanced: PreToolUse Blocking

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Edit",
        "command": "python validate_edit.py",
        "blocking": true
      }
    ]
  }
}

If the command exits non-zero, the tool call is blocked.

FAQ

Q: Do hooks slow down Claude Code? A: Hooks run synchronously, so heavy commands add latency. Keep hooks fast (< 2s) or make them async.

Q: Can hooks modify Claude's behavior? A: Yes, hook stdout is fed back as context. You can guide Claude's next action.

Q: Where do I put the settings file? A: .claude/settings.json in your project root (project-level) or ~/.claude/settings.json (global).