Skills are folders of instructions and resources that teach ChatGPT and Codex how to complete repeatable workflows. A plugin can include one skill or a group of related skills.
Each skill has a SKILL.md file with:
- A name.
- A description that tells the model when to consider the skill.
- Instructions for completing the workflow.
- Optional references, scripts, templates, and other assets.
When to use a skill
Use a skill when the model can complete a use case with instructions, examples, bundled resources, and tools it already has.
For example, a skill can define how to:
- Turn meeting notes into a recap and follow-up.
- Apply an organization’s writing or review standards.
- Generate a report from files the user provides.
- Follow a repeatable debugging or deployment procedure.
Add an MCP server when the workflow also needs live data, authentication, controlled actions, or code that runs on infrastructure you operate.
How skills activate
The model first sees skill metadata, including the name and description. It loads the complete instructions when the user’s request matches the skill or the user invokes it directly.
Write descriptions around the user goal and the conditions that should trigger the workflow. Keep detailed steps and output requirements in the instruction body.
Skills in a plugin
Skills are the workflow layer of a plugin. They can:
- Work on their own.
- Guide the model through tools exposed by the plugin’s MCP server.
- Package organization-specific procedures with reusable templates and references.
Skills and MCP tools should have clear, complementary roles. A skill explains how to complete the workflow; an MCP server provides live information and enforces controlled actions.
Continue with Build skills to create, test, and package a skill.