Comparison
Codex skills vs prompts
A prompt is usually a one-time instruction. A skill is a reusable operating package. Both can guide an agent, but they solve different problems.
Where prompts work well
Prompts are fast for one-off tasks, exploration, or lightweight instructions that do not need versioning. They are easy to paste and adjust, but they are also easy to lose or accidentally change.
Where skills are stronger
Skills are stronger when the workflow repeats. They can carry examples, verification rules, tool boundaries, and supporting files. They are easier to catalog, hash, download, review, and eventually expose through a remote MCP registry.
For a public skill library, the registry model also makes quality control possible: each item can have a stable ID, category, tags, risk status, and a download package.