Quick Tip: Claude Code Hooks — Automate Your Workflow

Hooks are commands that run automatically at specific points in Claude Code's lifecycle. Unlike CLAUDE.md instructions (which Claude may ignore), hooks are deterministic: if the condition is met, they always execute. Three handler types cover everything from simple validations to AI-powered verification.

For a complete guide with 5 essential hooks and advanced patterns, see the full hooks article.

Result:

// ~/.claude/settings.json
{
  "hooks": {
    "PostToolUse": [{
      "matcher": "Write|Edit",
      "hooks": [{
        "type": "command",
        "command": "npx prettier --write \"$CLAUDE_FILE_PATH\""
      }]
    }]
  }
}

The 3 hook types

1. Command — Run a script

The most common. Receives context via stdin as JSON, and the exit code decides the outcome: 0 passes, 2 blocks.

{
  "hooks": {
    "PreToolUse": [{
      "matcher": "Bash",
      "hooks": [{
        "type": "command",
        "command": "echo $CLAUDE_TOOL_INPUT | jq -e '.command | test(\"rm -rf|--force|DROP TABLE\") | not'"
      }]
    }]
  }
}

This hook blocks destructive commands like rm -rf, --force, or DROP TABLE before they execute.

2. Prompt — Let the LLM decide

For subjective decisions a script can't handle. Claude evaluates context with a prompt in a single pass.

{
  "hooks": {
    "PreToolUse": [{
      "matcher": "Write|Edit",
      "hooks": [{
        "type": "prompt",
        "prompt": "Check that the code follows the project style guide. Block if it introduces console.log statements in production code. $ARGUMENTS"
      }]
    }]
  }
}

3. Agent — Subagent with tools

For complex verification. Spawns a subagent with access to Read, Grep, and Glob that can inspect files before deciding.

{
  "hooks": {
    "PreToolUse": [{
      "matcher": "Write|Edit",
      "hooks": [{
        "type": "agent",
        "prompt": "Verify that every new function has a corresponding test file. Check the test directory for matching test files. Block if tests are missing. $ARGUMENTS"
      }]
    }]
  }
}

Quick reference

Event	When it fires	Typical use
`PreToolUse`	Before a tool runs	Block dangerous actions
`PostToolUse`	After a successful tool	Format, lint, type-check
`Notification`	When Claude sends a notification	Custom desktop alerts
`Stop`	When Claude finishes its response	Final validation, auto-commit
`PreCompact`	Before context compression	Re-inject critical instructions
`SessionStart`	When a session begins	Environment setup

Type	AI involved	Best for
`command`	No	Binary validations (pass/fail)
`prompt`	Yes (single pass)	Subjective decisions
`agent`	Yes (multi-turn)	Complex verification with tools

Configuration

Hooks are defined in settings.json. Three scope levels:

~/.claude/settings.json — All projects
.claude/settings.json — Project-level (shareable with the team)
.claude/settings.local.json — Project-level (private)

The fastest way to create one: type /hooks inside Claude Code.

Official docs: Hooks · Hooks Guide