Use Hooks to Automatically Run Commands Before or After Claude's Tool Calls

Claude Code can do more than respond to prompts — it can trigger your own scripts automatically. Hooks are shell commands that run before or after specific tool calls, giving you programmatic control over Claude's actions.

// .claude/settings.json
{
  "hooks": {
    "Edit": {
      "post": ["vendor/bin/pint --dirty --format agent"]
    }
  }
}

This hook runs your PHP formatter every time Claude edits a file — no need to remember "run Pint after changes" because it happens automatically.

Hooks fire on specific tool names: Edit, Write, Bash, Read, or any tool Claude has access to. Use pre to run something before the tool executes (and optionally block it), or post to run something after.

{
  "hooks": {
    "Bash": {
      "pre": ["echo 'Running command...'"],
      "post": ["echo 'Command completed'"]
    },
    "Write": {
      "post": ["npm run lint:fix"]
    }
  }
}

A few practical uses:

• Auto-format — run Prettier, Pint, or Black after every edit or write
• Auto-lint — catch issues the moment Claude introduces them
• Audit logging — record every tool call for compliance or debugging
• Safety gates — use a pre hook on Bash to block commands matching dangerous patterns

Hooks run in your project root and inherit your shell environment, so they have access to the same tools and paths you use normally. If a pre hook exits with a non-zero status, the tool call is blocked.

Set up hooks once and your standards enforce themselves — no discipline required.

via Claude Code