Use Anthropic Hook Development safely

This guide complements Anthropic’s official Hook Development source. It does not replace checking the installed Claude Code version, reviewing the plugin, or obtaining approval from the responsible team.

Choose the event and objective

First define the event and the concrete objective. PreToolUse fits a check before an action, while PostToolUse fits a controlled review afterward. Stop and SubagentStop support completeness checks, and SessionStart supports context loading. Do not choose the broadest event when a narrower rule is sufficient.

Select the hook type

Use prompt hooks when context and judgment matter. Use command hooks for reproducible checks with clear inputs. Limit timeouts, tools, and file access. Every decision should be returned in an understandable form so a blocked workflow can be investigated.

Review the configuration

Distinguish the plugin file hooks/hooks.json from direct settings. Check that events are nested at the correct level and that matchers select exactly the intended tools. Treat JSON, file contents, and external responses as untrusted data. Do not activate a rule whose effects and fallback behavior have not been tested with harmless fixtures.

FAQ

What is Hook Development? It is an official Anthropic skill with guidance for event-driven hooks in Claude Code plugins, including prompt and command hooks.

Are prompt hooks automatically safer? No. They can make context-aware decisions but still require limits, review, and human approval.

When are changes loaded? Hooks load when a session starts. According to the provider, changes require a restart.

Can a hook solve every security issue? No. Hooks complement but do not replace access control, code review, testing, or monitoring.