Can I block specific actions using hooks?

Yes. Using events like PreToolUse or UserPromptSubmit, you can block an action by exiting the script with a specific exit code (exit 2) and providing feedback through stderr.

What is the Claude Code Hook System?

It is a specialized framework that allows you to run scripts automatically during various stages of a Claude Code session, such as when a user submits a prompt or before a tool is executed.

How do hooks improve automation reliability?

Unlike standard skill activation which has a ~20% success rate, hooks offer a 100% success rate for forced automation because they are triggered by specific session events rather than LLM inference.

How is data passed to the hook scripts?

Data is passed to hooks via stdin in JSON format. This ensures that scripts have access to session IDs and other relevant context without relying on environment variables.

Claude Code Hook System

Name: Claude Code Hook System
Author: chkim-su

bychkim-su

生産性とワークフロー

Orchestrates and routes event-driven automation scripts to customize Claude Code session behavior.

概要

The Hook System serves as the central entry point for managing automation within Claude Code. It provides a structured architectural framework to route users toward specific capabilities such as implementation patterns, templates, and SDK integrations. By utilizing hooks—scripts that auto-execute at specific lifecycle events like UserPromptSubmit or PreToolUse—developers can achieve 100% reliability in automation, far exceeding standard tool selection rates. This skill is essential for anyone looking to build robust gates, automated side effects, or complex multi-phase workflows directly into their AI-driven development environment.

主な機能

Event-driven routing for 10 distinct session events
Standardized JSON data passing for robust script integration
Comprehensive decision tree for skill and template selection
High-reliability automation (100% success rate for hooks)
0 GitHub stars
Support for blocking/modifying actions via gate patterns

ユースケース

Automating documentation updates as side effects of code changes
Enforcing security or style gates before tool execution
Creating complex, state-based multi-phase development workflows

概要

主な機能

Event-driven routing for 10 distinct session events
Standardized JSON data passing for robust script integration
Comprehensive decision tree for skill and template selection
High-reliability automation (100% success rate for hooks)
0 GitHub stars
Support for blocking/modifying actions via gate patterns

ユースケース

Automating documentation updates as side effects of code changes
Enforcing security or style gates before tool execution
Creating complex, state-based multi-phase development workflows