# Writing Hookify Rules

Should be used when the user asks to "create a hookify rule", "write a hook rule"...

- Repository: https://github.com/anthropics/claude-plugins-official (45706 stars)
- Category: Writing
- License: Apache-2.0
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add anthropics/claude-plugins-official --skill writing-hookify-rules -g -a claude-code -y`
Codex: `npx skills add anthropics/claude-plugins-official --skill writing-hookify-rules -g -a codex -y`
Cursor: `npx skills add anthropics/claude-plugins-official --skill writing-hookify-rules -g -a cursor -y`
Gemini CLI: `npx skills add anthropics/claude-plugins-official --skill writing-hookify-rules -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add anthropics/claude-plugins-official`

## Description

This skill should be used when the user asks to "create a hookify rule", "write a hook rule", "configure hookify", "add a hookify rule", or needs guidance on hookify rule syntax and patterns.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Writing Hookify Rules

## Overview

Hookify rules are markdown files with YAML frontmatter that define patterns to watch for and messages to show when those patterns match. Rules are stored in `.claude/hookify.{rule-name}.local.md` files.

## Rule File Format

### Basic Structure

```markdown
---
name: rule-identifier
enabled: true
event: bash|file|stop|prompt|all
pattern: regex-pattern-here
---

Message to show Claude when this rule triggers.
Can include markdown formatting, warnings, suggestions, etc.
```

### Frontmatter Fields

**name** (required): Unique identifier for the rule
- Use kebab-case: `warn-dangerous-rm`, `block-console-log`
- Be descriptive and action-oriented
- Start with verb: warn, prevent, block, require, check

**enabled** (required): Boolean to activate/deactivate
- `true`: Rule is active
- `false`: Rule is disabled (won't trigger)
- Can toggle without deleting rule

**event** (required): Which hook event to trigger on
- `bash`: Bash tool commands
- `file`: Edit, Write, MultiEdit tools
- `stop`: When agent wants to stop
- `prompt`: When user submits a prompt
- `all`: All events

**action** (optional): What to do when rule matches
- `warn`: Show message but allow operation (default)
- `block`: Prevent operation (PreToolUse) or stop session (Stop events)
- If omitted, defaults to `warn`

**pattern** (simple format): Regex pattern to match
- Used for simple single-condition rules
- Matches against command (bash) or new_text (file)
- Python regex syntax

**Example:**
```yaml
event: bash
pattern: rm\s+-rf
```

### Advanced Format (Multiple Conditions)

For complex rules with multiple conditions:

```markdown
---
name: warn-env-file-edits
enabled: true
event: file
conditions:
  - field: file_path
    operator: regex_match
    pattern: \.env$
  - field: new_text
    operator: contains
    pattern: API_KEY
---

You're adding an API key to a .env file. Ensure this file is in .gitignore!
```

The rest: https://github.com/anthropics/claude-plugins-official/blob/HEAD/plugins/hookify/skills/writing-rules/SKILL.md