Introduction

Hooks are automated scripts that execute in response to specific events during Claude Code sessions. They enable automation, validation, permission management, and custom workflows.

Think of hooks as tripwires you set up in advance. When a specific event fires — such as starting a new session, submitting a prompt, or Claude calling a tool — your hook script runs automatically. This gives you a way to inject custom behavior into Claude Code without manually intervening every time.

Why Hooks Matter

Without hooks, you'd need to repeat setup steps at the start of every session or manually enforce rules each time Claude takes an action. Hooks let you automate that. Common uses include loading project context on startup, validating tool calls before they execute, enforcing coding standards, and sending notifications when tasks complete.

How Hooks Are Configured

Hooks are defined in your settings.json file under the hooks key. Each hook specifies an event type and the shell command to run. Here's a basic example that prints a message when a session starts:

{
  "hooks": {
    "SessionStart": [
      {
        "type": "command",
        "command": "echo 'Session started at $(date)'"
      }
    ]
  }
}

Available Hook Events

• SessionStart — fires when a new Claude Code session begins
• UserPromptSubmit — fires when you send a message to Claude
• PreToolUse — fires before Claude executes a tool (useful for blocking or modifying calls)
• PostToolUse — fires after a tool finishes executing
• Stop — fires when Claude finishes its response

Key takeaway: hooks turn Claude Code from a reactive assistant into a customizable workflow engine. Start with a simple SessionStart hook to load context, then explore PreToolUse hooks when you want guardrails around what Claude can do.