ChatGPT Skills
A ChatGPT skill is a folder containing a SKILL.md file — instructions, and optionally scripts, references, and templates — that teaches ChatGPT or Codex how to complete a repeatable workflow. Skills ship inside plugins. A skill supplies the workflow; an MCP server supplies live data and actions.
What a skill is
A skill is a folder with a SKILL.md file at its root. That file carries a name, a description telling the model when to consider the skill, the instructions for completing the workflow, and optionally references, scripts, templates, and other assets. Skills describe when to use a workflow, which steps to follow, and what a successful result looks like. They are packaged and distributed inside plugins.
How a skill activates
The model first sees only the skill's metadata — its name and description. It loads the full instructions when your request matches the skill, or when you invoke it directly. This is why a skill's description matters so much in practice: it is written around the user goal and the conditions that should trigger the workflow, and it is the only part the model sees until the skill fires.
Skill vs MCP server
The boundary is clean in OpenAI's own documentation: the MCP server provides data, authentication, authorization, and actions; the skill provides reusable instructions, examples, and templates. A skill can define how to retrieve account activity and turn it into a customer briefing, or how to apply an organization's writing standards to a result. A skill can also work with no MCP server at all, when the workflow needs only packaged instructions.
Skills-only plugins, and why we don't score them
You can publish a plugin that contains skills and nothing else, and those listings sit in the same directory as MCP-backed apps. We do not put them in the rankings. Our seven criteria — usefulness, reliability, ease of use, setup, in-chat experience, privacy clarity, value — are built to compare integrations that connect to a real service and can break, rate-limit, or leak. Most of those dimensions are undefined for a folder of instructions with no service behind it. Scoring it anyway would produce a number with nothing underneath, which is the one thing this site does not do.