hooks-design

Hooks enable deterministic automation at lifecycle events like PreToolUse and PostToolUse. Design hooks by mapping your automation need to the right event, writing a Bash or Python script, and configuring it to execute without user interaction—ideal for auto-formatting, security checks, or linting after Claude edits files.

Hooks guarantee deterministic execution at exact moments; AI responses are probabilistic and may vary. Use hooks when you need "always" behavior—enforcing code style, blocking dangerous commands, or validating output. Reserve Claude interactions for decisions requiring reasoning.

Yes. Create a PreToolUse hook that inspects incoming Bash commands and rejects dangerous operations before execution. This enforces security rules deterministically without manual oversight, reducing errors and enhancing protection.

Use a PostToolUse hook that triggers after Claude writes or modifies files. Configure it to invoke your linter or formatter as a script, pass the edited file path as input, and ensure execution completes under 60 seconds with proper error handling.

Write hooks in Bash or Python. For Python, use UV to manage dependencies securely and efficiently. Keep scripts lightweight, deterministic, and optimized for fast execution to maintain responsiveness.

No. Hooks execute deterministically without user interaction or Claude involvement, running automatically at their mapped lifecycle events. This ensures consistent, hands-off enforcement and automation.