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by gmh5225gmh5225/awesome-skills84 stars
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Guide for creating Agent Skills: structure, best practices, and SKILL.md format for Claude Code, Codex, Gemini CLI, and other AI agents.

  • 1 file
  • 2.7 KB
  • Updated 8 months ago
  • GitHub
Use this Skill: https://skilld.dev/gh/gmh5225/awesome-skills/skill-creation

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SKILL.md

≈38 tokens for metadata: the name and description. ≈656 when used: this file.

Description uses 2.0% of example budget

Before choosing a Skill, your Agent reads its name and description. All available Skills share that space.

  • A shorter description leaves more room for other Skills. This entry exceeds our 1% size suggestion.

In our Claude Code example, all Skill names and descriptions share 8,000 characters. This Skill uses ≈159 characters, or 2.0%.

The 1% threshold is a size suggestion. Longer descriptions can still fit.

Your model, settings, and other Skills decide how much text your Agent can read.

Example settings and source

The example uses a 200k-token context and default Claude Code settings. The count includes the name, description, separators, and when_to_use when present. Codex also counts local file paths.

Skit's source and limits: Codex 0.160.1, Claude Code 2.1.292.

Skill Creation Guide

Scope

Use this skill when:

  • Creating new Agent Skills
  • Understanding SKILL.md format and conventions
  • Learning best practices for skill authoring

Skill Structure

skill-name/
├── SKILL.md          # Required: Instructions and metadata
├── scripts/          # Optional: Helper scripts
├── templates/        # Optional: Document templates
└── resources/        # Optional: Reference files

SKILL.md Format

Required Frontmatter

---
name: my-skill-name
description: A clear description of what this skill does and when to use it.
---

Body Structure

# Skill Name

Detailed description of the skill's purpose.

## When to Use This Skill

- Use case 1
- Use case 2

## Instructions

[Detailed instructions for the agent]

## Examples

[Real-world examples]

Best Practices

  1. Keep descriptions exhaustive: The frontmatter description helps agents decide when to trigger the skill.
  2. Focus on execution: The body should contain clear, actionable steps.
  3. Use progressive disclosure: Put detailed references in references/ folder.
  4. Include scripts for automation: Use helper scripts for deterministic operations.
  5. Keep SKILL.md under 500 lines: For optimal performance.
  6. Test across platforms: Verify skills work with Claude Code, Codex, etc.

Token Efficiency

Skills employ progressive disclosure architecture:

  1. Metadata loading (~100 tokens): Agent scans available skills
  2. Full instructions (<5k tokens): Load when skill is activated
  3. Bundled resources: Only load as needed

Platform-Specific Paths

Platform Project Path Global Path
Claude Code .claude/skills/ ~/.claude/skills/
Codex .codex/skills/ ~/.codex/skills/
Cursor .cursor/skills/ ~/.cursor/skills/
Gemini CLI .gemini/skills/ ~/.gemini/skills/
GitHub Copilot .github/skills/ ~/.copilot/skills/

Quality Checklist

  • Clear, actionable instructions
  • Includes real-world examples
  • Written for AI agents, not end users
  • Documents prerequisites and dependencies
  • Includes error handling guidance
  • Tested on target platform(s)

Full Resource List

For more detailed skill creation resources, complete link lists, or the latest information, use WebFetch to retrieve the full README.md:

https://raw.githubusercontent.com/gmh5225/awesome-skills/refs/heads/main/README.md

The README.md contains the complete categorized resource list with all links.

Source: SKILL.md on GitHub

No rule matched.

skilld matched fixed text patterns in SKILL.md and file names. Patterns miss obfuscated code.

skilld run checks every file with the same patterns. It asks for approval before it loads a Skill with a behavior marked Needs approval.

No third-party reports yet.

Signed by skilld. This ties the file your Agent reads to that commit on GitHub. It does not review the instructions.

Last checked against GitHub 7 hours ago.

updated 8 months ago

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