What is SKILL.md? The open standard for Claude AI skills explained

SKILL.md is an open plain-text standard — a single Markdown file that lives in the root of any GitHub repository and tells an AI coding agent (Claude Code, Cursor, Windsurf, and others) exactly what a skill does, how to trigger it, and what rules it should follow. Think of it as a package.json for AI behaviour. Instead of re-explaining your preferred coding style, your review checklist, or your deployment workflow in every new conversation, you write it once in SKILL.md and install it globally. What goes inside a SKILL.md file? ---------------------------------- A minimal SKILL.md has three sections: name: frontend-shadcn-builder description: > Builds React components using shadcn/ui, Tailwind, and TypeScript. Follows the project's component library conventions. triggers: - build a component - create a UI - add a shadcn A complete skill also includes: - A `rules` section (what the skill should always or never do) - An `examples` section (sample inputs and expected outputs) - A `version` field (for changelog tracking) - A `license` field (MIT, Apache-2.0, etc.) The full specification is documented at claudeskil.com/docs. Why does the standard matter? ------------------------------ Before SKILL.md, sharing AI "prompts" meant copy-pasting walls of text into a Discord channel. The quality degraded instantly. There was no versioning, no review, no way to know if a prompt had been tested or just thrown together. SKILL.md changes that. Because it's a file in a Git repo, every skill has: - A commit history (you can see when it changed and why) - Issues (users can report bugs) - Stars (popularity signal) - Releases (versioned, stable snapshots) It turns a prompt into software. How do agents read it? ----------------------- When you run `claude skills add frontend-shadcn-builder`, Claude Code fetches the SKILL.md from the repository, validates the schema, and injects the relevant sections into the system prompt for matching conversations. The skill is active until you remove it — no re-pasting required. Cursor, Windsurf and other MCP-compatible agents follow the same pattern via the open spec. How to create your own SKILL.md -------------------------------- 1. Create a new GitHub repo (e.g. `my-skill`) 2. Add a `SKILL.md` file to the root 3. Fill in `name`, `description`, `triggers`, and `rules` 4. Push and open-source it (MIT is the community default) 5. Submit to ClaudeSkill at claudeskil.com/submit Your skill will be reviewed within 24 hours and listed on the marketplace once approved. The SKILL.md ecosystem today ------------------------------ As of May 2026, ClaudeSkill lists over 2,800 open-source skills across 40+ categories — from frontend engineering and data science to SEO, video editing, and SQL. Every one follows the SKILL.md standard, which means they all work the same way regardless of which agent you use. The standard is community-maintained and intentionally minimal. The goal is for any developer to be able to read a SKILL.md file cold and understand it in 30 seconds.