Agent Skills

Agent skills are plain .md files + other bundled files that provide Agents with additional capabilities and context.

Developed by Anthropic but now an open standard.

Format

A skill is just a markdown file with a little frontmatter (name, description and a few more optional fields), followed by the instructions the agent reads once the skill triggers:

---
name: my-skill
description: When to reach for this skill, in one line.
license: Apache-2.0
metadata:
  author: example-org
  version: "1.0"
---

# My Skill

The steps the agent should follow once this skill is loaded.

Frontmatter

Field	Required	Constraints
name	Yes	Max 64 characters. Lowercase letters, numbers, and hyphens only. Must not start or end with a hyphen.
description	Yes	Max 1024 characters. Non-empty. Describes what the skill does and when to use it.
license	No	License name or reference to a bundled license file.
compatibility	No	Max 500 characters. Indicates environment requirements (intended product, system packages, network access, etc.).
metadata	No	Arbitrary key-value mapping for additional metadata.
allowed-tools	No	Space-separated string of pre-approved tools the skill may use.

Reference

https://agentskills.io/specification for the specification.

https://www.skills.sh/ has become the de-facto skills directory.

These are the Agent skills I use .