What is a Skill?
A SKILL.md file teaches your AI coding assistant domain-specific knowledge about a service's API — the things that aren't captured in tool names or parameter descriptions.
Skills are an open standard supported by 27+ AI agents including Claude Code, Cursor, Codex, Gemini CLI, and VS Code.
What's in a Skill?
A skill encodes what you'd learn after using an API for a week. It doesn't list tools — your AI already has list_tools for that.
Domain Knowledge
Data model hierarchies, object relationships, and how a service organizes its concepts. The stuff you'd learn after using the API for a week.
Workflow Patterns
Multi-step sequences like "create Customer before Subscription" or "look up pipeline stages before setting a deal stage." The ordering the AI wouldn't know.
Gotchas & Constraints
Non-obvious behaviors, common mistakes, and API quirks — like "feature flag deletion is permanent" or "use $pathname instead of $current_url for breakdowns."
Progressive Loading
Skills use a lightweight discovery model. Your AI reads the name and description (~100 tokens) at startup and only loads the full skill when a matching task is detected.
What a Skill is Not
Not a tool listing
Your AI already gets tool names, descriptions, and full parameter schemas from MCP. A skill that repeats this is wasted tokens.
Not setup instructions
Authentication, credential configuration, and API keys are handled by the MCP platform. Skills focus on how to use the API effectively, not how to connect.
Skills + MCP Bundles
MCPBundles skills are different from generic skills — they're written for the exact tools in each MCP server and backed by real authenticated API access.
Skill
Teaches domain knowledge
MCP Server
Provides authenticated tool access
Together, your AI knows how and can interact with third-party services.
Works with Every Major AI Agent
Save the SKILL.md file to the right location in your project and your agent picks it up automatically.
.claude/skills/{name}/SKILL.md.cursor/rules/{name}.md.agents/skills/{name}/SKILL.md.github/copilot-instructions.md.windsurfrules/{name}.md.agents/skills/{name}/SKILL.md