Claude Code Hooks — Custom Automation Recipes

What it is

Claude Code Hooks are shell commands that execute automatically before or after specific tool uses within Claude Code sessions. They work like git hooks but for your AI coding assistant. This collection provides ready-to-use recipes for auto-formatting code, running tests, sending notifications, scanning for security issues, and enforcing workflow policies.

The collection targets developers using Claude Code who want to enforce code quality standards and automate repetitive tasks around AI-generated code. Each recipe is a JSON snippet you paste into your settings.json.

How it saves time or tokens

Without hooks, you need to manually run formatters, linters, and tests after every file Claude Code writes or edits. Hooks automate this entire class of tasks. A PostToolUse hook on Write and Edit operations means every generated file is automatically formatted, and pre-commit quality checks happen without manual intervention.

The token estimate for this workflow is approximately 2,600 tokens. Hooks run as shell commands outside the LLM context, so they consume zero tokens.

How to use

1. Open Claude Code settings:

claude config

Or edit ~/.claude/settings.json directly.

1. Add a hook to auto-format every file Claude writes:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit",
        "command": "npx biome check --write $CLAUDE_FILE_PATH 2>/dev/null || npx prettier --write $CLAUDE_FILE_PATH 2>/dev/null || true"
      }
    ]
  }
}

1. Claude Code now auto-formats every file it creates or modifies.

Example

Multiple hook recipes for different automation needs:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "command": "echo 'Running: '$CLAUDE_COMMAND >> ~/.claude/audit.log"
      }
    ],
    "PostToolUse": [
      {
        "matcher": "Write|Edit",
        "command": "npx biome check --write $CLAUDE_FILE_PATH 2>/dev/null || true"
      }
    ],
    "Stop": [
      {
        "command": "terminal-notifier -message 'Claude Code finished' -title 'Done' 2>/dev/null || true"
      }
    ]
  }
}

Hook event types:

PreToolUse   -- Before a tool runs (can block execution)
PostToolUse  -- After a tool completes
Notification -- When Claude sends a notification
Stop         -- When Claude finishes a response

Related on TokRepo

• AI Tools for Automation -- Workflow automation tools
• AI Tools for Coding -- Developer productivity integrations

Common pitfalls

• Hook commands run synchronously. A slow command (e.g., running a full test suite on every file save) blocks Claude Code until it completes. Keep hook commands fast or run them asynchronously with &.
• The $CLAUDE_FILE_PATH variable is only available for Write and Edit tool matchers. Other tools have different environment variables. Check the Claude Code documentation for the full variable list.
• Hooks that exit with a non-zero status on PreToolUse can block the tool from running. Always add || true to PostToolUse hooks to prevent false failures from interrupting the workflow.