Definition
What are Codex skills?
Codex skills are reusable instruction packages that teach an AI coding agent how to perform a specific workflow. A good skill usually includes a SKILL.md file, operating boundaries, examples, tool expectations, and any supporting files needed to make the workflow repeatable.
The short definition
A Codex skill is a portable workflow module for an AI agent. Instead of rewriting the same instructions every time, the agent can read the skill and apply a consistent process for tasks such as code review, PDF parsing, GitLab automation, SQL optimization, or document conversion.
The useful part is not only the prompt text. A skill can define when it should be used, what files or tools it depends on, how to verify the output, and what safety limits apply before the agent takes action.
What a skill should contain
A practical skill should have a clear name, a description, a trigger condition, step-by-step operating guidance, and examples or references when the task is complex. It should also explain risks, such as secrets, destructive commands, paid APIs, or local file changes.
ShowUskills packages public skills as downloadable zip files so users can inspect the contents before using them in a local agent environment.