Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add instructions/decider/claude-hooks/claude-mdgit clone --depth 1 https://github.com/decider/claude-hooksWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/decider/claude-hooks/claude-md)<a href="https://agentmods.dev/instructions/decider/claude-hooks/claude-md"><img src="https://agentmods.dev/badge/instructions/decider/claude-hooks/claude-md.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00445 | $0.00445 |
| Opus 5 | $0.00222 | $0.00222 |
| Sonnet 5 | $0.00089 | $0.00089 |
| Haiku 4.5 | $0.00044 | $0.00044 |
Grade A, and why
claude-hooks CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Claude Hooks
A Python-based hook system for Claude Code that provides automatic validation and quality checks.
Overview
This project provides Python hooks that integrate with Claude Code (claude.ai/code). Hooks allow you to run validation, linting, type checking, and other quality checks automatically during Claude sessions.
Available Hooks
Built-in Hooks
Code Quality
- code-quality-validator: Enforces clean code standards (function length, nesting, etc.) after file edits
Package Management
- check-package-age: Prevents installation of outdated npm/yarn packages
Notifications
- task-completion-notify: System notifications for completed tasks (optional)
Installation
Run the installer to set up hooks in your project:
python3 install-hooks.py
Configuration
Hierarchical Configuration System
The hook system supports flexible, directory-specific configurations:
- Root Configuration:
.claude/hooks.jsondefines default hooks - Directory Overrides: Any directory can have
.claude-hooks.json - Configuration Inheritance: Settings cascade with local overrides
Example:
project/
├── .claude/hooks.json # Default settings
├── backend/
│ └── .claude-hooks.json # Stricter Python rules
└── frontend/
└── .claude-hooks.json # Different JS/React rules
Hook Introspection
# See all hooks in your project
python3 hooks/list_hooks.py list
# Check which hooks apply to a specific file
python3 hooks/list_hooks.py explain src/app.py
Architecture Notes
- Written in Python for portability (no external dependencies)
- Hook scripts stored in
.claude/hooks/ - Main configuration in
.claude/hooks.json(JSON format) - Settings.json in
.claude/settings.jsonfor Claude integration - Three universal entry points: PreToolUse, PostToolUse, Stop
- Each hook validates specific conditions and provides feedback
- Hooks receive configuration via CLAUDE_HOOK_CONFIG environment variable
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 4d ago First seen · 64 lines · 445 tokens per session scan A c3e44f1e8d6e
claude-hooks CLAUDE.md is an instructions file published in the GitHub repository decider/claude-hooks (75 stars, last pushed 1y ago), licensed MIT. It adds 445 tokens to every session, about $0.0022 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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Instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.