# Agent Skills Specification

> The open standard behind SKILL.md skills, with the spec and list of supporting tools.

- Type: Resource
- Use case: Build Skills & MCP
- Works with: Claude Code, Claude apps, OpenAI Codex, Gemini CLI, Cursor, VS Code & Copilot, Windsurf, ChatGPT
- Website: https://agentskills.io
- Author: Agentic AI Foundation
- Pricing: Free
- License: Open standard
- Listed on MetaSkill: https://meta-skill.com/resources/agent-skills-specification

## About

agentskills.io hosts the Agent Skills specification: the SKILL.md format, frontmatter fields, progressive disclosure and how agents should load skills. Anthropic created the format, published it as an open standard in December 2025, and in October 2026 handed it to the Agentic AI Foundation under the Linux Foundation.

Check the site's adopter list to see which agents support skills.