Writing Hookify Rules

What it does

When your agent uses it

• Creating a rule that warns before dangerous rm commands
• Blocking console.log or other patterns from being written into code
• Toggling or editing an existing hookify rule
• Looking up hookify frontmatter fields and operators

Example prompts

• “Create a hookify rule that warns when a command contains rm -rf.”
• “Write a hookify rule that blocks edits to .env files.”
• “Add a hookify rule that stops console.log from being added to production code.”

Requirements

• The hookify plugin for Claude Code

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

1. 1Identify unwanted behavior
2. 2Determine which tool is involved (Bash, Edit, etc.)
3. 3Choose event type (bash, file, stop, etc.)
4. 4Write regex pattern
5. 5Create .claude/hookify.{name}.local.md file in project root
6. 6Test immediately - rules are read dynamically on next tool use

What it can do on your machine

Read from SKILL.md and the folder at commit b78ac49. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • python3

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names these keys or tokens, usually read from environment variables:

  • API_KEY

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Writing Hookify Rules loads about 2.1k tokens when it runs. Until then it costs about 53 tokens; SKILL.md has 639 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~53

When it runs · the whole SKILL.md, loaded when a task matches

~2.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

• NoteMentions a .env fileSKILL.md:82

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

• NoteMentions a .env fileSKILL.md:327

  s-warning.local.md` - Warn about editing .env files

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from anthropics/claude-plugins-official at commit b78ac49, republished under its Apache-2.0 licence (© anthropics). 639 words, ~2,104 tokens.

name

writing-hookify-rules

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.

version

0.1.0

---
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.

event: bash
pattern: rm\s+-rf

---
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!

⚠️ **Console.log detected!**

You're adding console.log to production code.

**Why this matters:**
- Debug logs shouldn't ship to production
- Console.log can expose sensitive data
- Impacts browser performance

**Alternatives:**
- Use a proper logging library
- Remove before committing
- Use conditional debug builds

---
event: bash
pattern: sudo\s+|rm\s+-rf|chmod\s+777
---

Dangerous command detected!

---
event: file
pattern: console\.log\(|eval\(|innerHTML\s*=
---

Potentially problematic code pattern detected!

---
event: file
conditions:
  - field: file_path
    operator: regex_match
    pattern: \.tsx?$
  - field: new_text
    operator: regex_match
    pattern: console\.log\(
---

Console.log in TypeScript file!

---
event: stop
pattern: .*
---

Before stopping, verify:
- [ ] Tests were run
- [ ] Build succeeded
- [ ] Documentation updated

---
event: prompt
conditions:
  - field: user_prompt
    operator: contains
    pattern: deploy to production
---

Production deployment checklist:
- [ ] Tests passing?
- [ ] Reviewed by team?
- [ ] Monitoring ready?

rm\s+-rf         Matches: rm -rf, rm  -rf
console\.log\(   Matches: console.log(
(eval|exec)\(    Matches: eval( or exec(
chmod\s+777      Matches: chmod 777, chmod  777
API_KEY\s*=      Matches: API_KEY=, API_KEY =

python3 -c "import re; print(re.search(r'your_pattern', 'test text'))"

pattern: log    # Matches "log", "login", "dialog", "catalog"

pattern: rm -rf /tmp  # Only matches exact path

---
name: my-rule
enabled: true
event: bash
pattern: dangerous_command
---

Warning message here

---
name: my-rule
enabled: true
event: file
conditions:
  - field: file_path
    operator: regex_match
    pattern: \.ts$
  - field: new_text
    operator: contains
    pattern: any
---

Warning message

© anthropics, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in plugins/hookify/skills/writing-rules of anthropics/claude-plugins-official.

Open the folder on GitHubat commit b78ac49

Used in 6 other repositories

We found 24 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 6 other GitHub owners. This page covers the copy in anthropics/claude-plugins-official, which our catalogue first saw on October 7, 2026.

• xiaoyuge886/aigcplugins/claude-plugins-official-main/plugins/hookify/skills/writing-rules
• aiskillstore/marketplaceskills/writing-hookify-rulesskills/davila7/writing-hookify-rules+2 more
• LING71671/Open-ClaudeCodeplugins/hookify/skills/writing-rules
• davila7/claude-code-templatescli-tool/components/skills/productivity/writing-rules
• Microck/ordinary-claude-skillsskills_all/rule-identifierskills_categorized/mobile/rule-identifier+14 more
• infometa/workbuddyskillsplugins/codebuddy-plugins-official/plugins/hookify/skills/writing-rules