Skill vs Rule vs MCP: When to Use Each
Compare Agent Skills, Cursor Rules, and MCP servers. Learn which tool fits workflows, persistent context, and external integrations.
Updated 2026-06-22
Choose the right extension mechanism for your AI workflow.
| Feature | Skill | Rule | MCP |
|---|---|---|---|
| Activation | On-demand when relevant | Always injected | Tool calls |
| Format | SKILL.md folder | .mdc in .cursor/rules/ | MCP server |
| Best for | Specialized workflows | Project conventions | Live external data |
| Portability | Cross-platform | Cursor-specific | Any MCP client |
Use a Skill when you need procedural knowledge activated contextually (code review, PDF generation).
Use a Rule when every conversation needs the same constraints (coding style, file patterns).
Use MCP when the agent needs real-time access to APIs, databases, or browsers.
FAQ
When should I use a Skill instead of a Rule?
Use Skills for on-demand specialized workflows the agent activates when relevant (code review, PDF generation). Use Rules for always-on project conventions injected into every conversation (coding style, file patterns).
When should I use MCP instead of a Skill?
MCP connects agents to live external tools and APIs (databases, browsers, SaaS). Skills package procedural knowledge and scripts. Use MCP when you need real-time data; use Skills when you need repeatable instructions.