SkillCannon

What Are Claude Skills (and Agent Skills)?

Published May 30, 2026

Claude skills, also called agent skills, are packaged instructions that teach an AI coding agent how to perform a specific task the right way. Each skill is a SKILL.md file: a short description the agent matches against, plus a body of instructions it follows when the task comes up. Instead of re-explaining your process every time, you install the skill once and the agent applies it on demand.

Anthropic's Help Center owns the official definition. This guide is the plain-language, cross-agent version, with links to skills you can actually use.

The SKILL.md format in one minute

A skill is a folder with a SKILL.md at its root. The frontmatter holds a name and a description; the body holds the instructions. The agent reads only the description until the skill is relevant, then loads the full body and any bundled files. That progressive disclosure keeps the agent's context lean.

The three types of skills

  1. Built-in skills, shipped with the agent or its platform.
  2. Community skills, published by other people and installed from a repo or marketplace.
  3. Custom skills, ones you write for your own team's process.

Most teams use a mix: a few community skills for common jobs, and a handful of custom ones for the work that is specific to them.

Why "agent skills" is the durable name

The format is not Claude-only. Codex and OpenCode read SKILL.md skills too, so the vendor-neutral term agent skills is increasingly accurate. We organize our catalog around that reality and tag every entry with how it behaves on each agent.

Where to go next

Skills mentioned

  • Agentic SEO Skill

    Top pick

    Deterministic, LLM-first SEO and GEO audits for sites, blogs, and repos, with script-backed evidence and prioritized, confidence-labeled fixes.

    • Claude Code: Works
    • Codex: Works
    • OpenCode: Unverified
    Read the full take

Frequently asked questions

Are Claude skills the same as MCP?
No. A skill is packaged instructions that teach the agent how to do a task. MCP is a protocol that connects an agent to external tools and data. A skill can use an MCP server, but they solve different problems: skills are know-how, MCP is connectivity.
Do Claude skills work in Codex and OpenCode?
Mostly yes. SKILL.md is an open format. Codex reads .agents/skills and OpenCode reads its own plus .claude/skills and .agents/skills. What degrades across agents is Claude-specific plumbing like hooks and some MCP setups, which is why each skill should carry a compatibility note.
Do I need to be a developer to use skills?
No. Installing a skill is usually copying a folder into a skills directory or running one install command. Using it is just asking the agent to do the task the skill covers.
Are skills and agent skills different things?
They are the same idea under two names. Anthropic popularized the term Claude skills; agent skills is the vendor-neutral name for the same SKILL.md format now adopted across multiple coding agents.