Claude Hook Developer FAQs

Question 1

How do I block an action using a hook?

Accepted Answer

In a command hook, exiting with code 2 will deny the action and display your error message; in a prompt hook, you instruct Claude to set the permissionDecision to 'deny' based on specific criteria.

Question 2

What is a Claude Code hook?

Accepted Answer

A hook is an event-driven mechanism that allows you to execute scripts or prompts at specific points in Claude's execution lifecycle, such as before a tool is used or when a session starts.

Question 3

Which event should I use to validate file edits?

Accepted Answer

You should use the PreToolUse event combined with a matcher for 'Write|Edit' to intercept and validate file changes before they are actually written to disk.

Question 4

What is the difference between a command hook and a prompt hook?

Accepted Answer

Command hooks execute external scripts (like Node.js) and use exit codes for logic, while prompt hooks use Claude's own reasoning to evaluate conditions semantically.

Question 5

What environment variables are available for pathing?

Accepted Answer

Plugin-level hooks should use ${CLAUDE_PLUGIN_ROOT} for absolute paths, whereas project-specific hooks utilize the "$CLAUDE_PROJECT_DIR" variable.

Claude Hook Developer

Key Features

Use Cases

Claude Hook Developer

Key Features

Use Cases