Skill

A skill is usually a folder with a main file, SKILL.md, holding a name, a description of when to use it and the instructions. It can also include templates, examples and scripts.

The agent reads only the name and description of each available skill. When a request matches one, it loads the rest. That way you can have many skills without filling the context window.

Skill, system prompt and tool

• The system prompt applies to everything, always.
• A skill comes in only when the task calls for it.
• A tool is an action the agent performs, such as reading a file or calling an API. A skill can teach how to use tools.