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PreToolUse

Hook Official

Hookify plugin - User-configurable hooks from .local.md files

0Other

Fires on

PreToolUse

Immediately before a tool runs — this is where an action can be denied.

Where this sits in a session

  1. Session start→
  2. Prompt submitted→
  3. Prompt expansion→
  4. Before tool use→
  5. After tool use→
  6. Notification→
  7. Before compaction→
  8. Subagent finished→
  9. Turn finished→
  10. Session end

Can block — This hook is able to deny the action or send Claude back to work.

What it runs

Executed automatically when the event fires — no prompt, no confirmation.

command· timeout 10s
python3 "${CLAUDE_PLUGIN_ROOT}/hooks/pretooluse.py"

Install it yourself

Paste into .claude/settings.json to run this hook without installing the whole plugin. Adjust the paths to point at your own copy of the scripts.

settings.json
{
  "hooks": {
    "PreToolUse": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "python3 \"${CLAUDE_PLUGIN_ROOT}/hooks/pretooluse.py\"",
            "timeout": 10
          }
        ]
      }
    ]
  }
}

Source

Read this before installing — it runs on your machine with your permissions.

#!/usr/bin/env python3
"""PreToolUse hook executor for hookify plugin.

This script is called by Claude Code before any tool executes.
It reads .claude/hookify.*.local.md files and evaluates rules.
"""

import os
import sys
import json

# Add plugin root to Python path for imports
PLUGIN_ROOT = os.environ.get('CLAUDE_PLUGIN_ROOT')
if PLUGIN_ROOT and PLUGIN_ROOT not in sys.path:
    sys.path.insert(0, PLUGIN_ROOT)

try:
    from core.config_loader import load_rules
    from core.rule_engine import RuleEngine
except ImportError as e:
    # If imports fail, allow operation and log error
    error_msg = {"systemMessage": f"Hookify import error: {e}"}
    print(json.dumps(error_msg), file=sys.stdout)
    sys.exit(0)


def main():
    """Main entry point for PreToolUse hook."""
    try:
        # Read input from stdin
        input_data = json.load(sys.stdin)

        # Determine event type for filtering
        # For PreToolUse, we use tool_name to determine "bash" vs "file" event
        tool_name = input_data.get('tool_name', '')

        event = None
        if tool_name == 'Bash':
            event = 'bash'
        elif tool_name in ['Edit', 'Write', 'MultiEdit']:
            event = 'file'

        # Load rules
        rules = load_rules(event=event)

        # Evaluate rules
        engine = RuleEngine()
        result = engine.evaluate_rules(rules, input_data)

        # Always output JSON (even if empty)
        print(json.dumps(result), file=sys.stdout)

    except Exception as e:
        # On any error, allow the operation and log
        error_output = {
            "systemMessage": f"Hookify error: {str(e)}"
        }
        print(json.dumps(error_output), file=sys.stdout)

    finally:
        # ALWAYS exit 0 - never block operations due to hook errors
        sys.exit(0)


if __name__ == '__main__':
    main()

Shipped by 1 plugin

Installing any of these installs this hook.

hookify32.9K

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