Skill
Reusable expertise or a workflow that should load only for matching tasks.
Which skill format does your agent need?
The expert logic can stay the same. Installation, file format, and activation differ. This comparison maps formats, not model quality.
Sources reviewed: 29 Aug 2026
Four agents. Two format families.
Codex, Claude Code, and Gemini CLI use packaged Agent Skills with SKILL.md. Cursor uses Project Rules in .mdc format.
AgentFormatProject pathScopeSource
Skill, rule, prompt, or MCP?
These are not synonyms. Choose based on the actual user job.
Repository rule
Persistent project convention for codebase, language, architecture, or permission boundaries.
Prompt
A one-time instruction without installation, version folder, or progressive resources.
MCP
A connection to data and actions. MCP provides capabilities; the skill explains when and how to use them safely.
No “best agent” ranking.
This page documents publicly supported formats and installation models. Model quality, SEO quality, and reliability require separate reproducible tests with identical inputs, versions, and rubric.