skill-lint

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A lightweight Node.js CLI tool for linting and validating OpenClaw SKILL.md files before publishing to ClawHub.

Overview

skill-lint ensures that your OpenClaw skills follow best practices and are ready for publication. It validates SKILL.md file structure, required fields, metadata completeness, and markdown content quality.

Features

• Frontmatter Validation - Checks YAML structure and required fields (name, description)
• Metadata Inspection - Validates metadata.openclaw structure and installation methods
• Installation Validation - Ensures install entries have correct format (brew, apt, manual, npm, pip)
• Content Validation - Checks markdown body for required sections (Purpose, When to Use, Setup)
• Emoji Validation - Warns if display emoji is missing for better ClawHub discoverability
• Description Quality - Validates description length (20-200 chars) for clarity
• Colored Output - Human-readable terminal output with errors, warnings, and info
• JSON Output - Machine-readable JSON output with --json flag
• No External Dependencies - Built with Node.js built-ins only

Installation

npm install -g @openclawHQ/skill-lint

Or install locally:

npm install --save-dev @openclawHQ/skill-lint

Usage

Basic Validation

Validate a SKILL.md file in the current directory:

skill-lint

Validate a specific file:

skill-lint path/to/SKILL.md

Options

-h, --help         Show help message
-v, --version      Show version number
-q, --quiet        Suppress info messages (errors and warnings only)
--json             Output results as JSON for programmatic use

Examples

Validate with minimal output:

skill-lint -q SKILL.md

Get JSON output for CI/CD integration:

skill-lint --json path/to/SKILL.md

Validation Rules

Errors (must fix before publishing)

• required-fields - Missing name or description in frontmatter
• install-missing-id - Install method missing required id field
• install-missing-kind - Install method missing required kind field
• install-no-target - Install method missing target (formula/package/steps)
• install-missing-formula - Brew install method requires formula field
• install-missing-package - APT install method requires package field
• install-missing-steps - Manual install method requires steps array

Warnings (recommended to fix)

• name-format - Skill name should be kebab-case (e.g., my-skill, not MySkill)
• name-length - Skill name longer than 50 characters
• description-length - Description shorter than 20 or longer than 200 characters
• description-format - Description should start with capital letter
• missing-emoji - No emoji in metadata.openclaw.emoji
• emoji-format - Emoji should be a single character
• install-invalid-kind - Install kind is not one of: brew, apt, manual, npm, pip
• missing-sections - Body missing recommended sections (Purpose, When to Use, Setup)
• empty-body - Skill description body is empty
• no-install - No installation methods specified
• no-examples - Consider adding Examples section

Info Messages (best practices)

• metadata-structure - Consider adding metadata.openclaw section
• no-examples - Consider adding Examples section with usage patterns

SKILL.md Format

A valid SKILL.md file requires:

---
name: skill-name
description: "Brief description of what this skill does"

# Optional: Extended metadata for ClawHub
metadata:
  openclaw:
    emoji: 🔧
    requires:
      bins:
        - required-binary
      env:
        - REQUIRED_ENV_VAR
    install:
      - id: brew
        kind: brew
        formula: package-name
        label: "Install via Homebrew"
      - id: manual
        kind: manual
        label: "Manual installation"
        steps:
          - "Step 1"
          - "Step 2"
---

## Purpose

Describe what this skill does and its primary use cases.

## When to Use

Explain scenarios where this skill is appropriate.

## When NOT to Use

Explain scenarios where alternatives would be better.

## Setup

Installation and configuration instructions.

### Prerequisites

List required tools and dependencies.

### Local Testing

How to install and test the skill locally.

## Commands / Actions

List and describe available commands.

## Examples

Provide copy-paste-ready usage examples.

## Notes

- **Limitations**: Known limitations and edge cases
- **Performance**: Expected performance characteristics
- **Troubleshooting**: Common issues and solutions
- **Security**: Security considerations for API keys, etc.

Exit Codes

• 0 - No errors found (warnings and info may still be present)
• 1 - One or more errors found

Integration Examples

Pre-commit Hook

Add to .git/hooks/pre-commit:

#!/bin/bash
skill-lint SKILL.md || exit 1

GitHub Actions

Add to .github/workflows/validate.yml:

name: Validate SKILL.md
on: [push, pull_request]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
      - run: npm install -g @openclawHQ/skill-lint
      - run: skill-lint SKILL.md

npm script

Add to package.json:

{
  "scripts": {
    "validate": "skill-lint SKILL.md"
  }
}

Development

Project Structure

.
├── bin/
│   └── skill-lint.js        # CLI entry point
├── src/
│   ├── parser.js            # SKILL.md parser
│   ├── rules.js             # Validation rules
│   └── reporter.js          # Output formatting
├── test/
│   ├── parser.test.js       # Parser tests
│   ├── rules.test.js        # Rules tests
│   ├── reporter.test.js     # Reporter tests
│   ├── integration.test.js  # Integration tests
│   └── fixtures/            # Test fixtures
├── package.json
└── README.md

Running Tests

npm test

All tests use Node.js built-in test runner (Node 18+).

Adding New Rules

1. Add validation function to src/rules.js
2. Add tests in test/rules.test.js
3. Update README with rule documentation
4. Run tests to verify: npm test

Future Enhancements

• Auto-fix capabilities for common issues
• Support for skill templates and scaffolding
• Integration with ClawHub API for pre-publish checks
• Custom rule configuration
• Multiple file validation
• Watch mode for development

Contributing

Contributions welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Add tests for new functionality
4. Ensure all tests pass: npm test
5. Submit a pull request

License

MIT - See LICENSE file

Links

• OpenClaw - Main project
• ClawHub - Official skill registry
• SKILL.md Specification - Full format documentation

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