MCP Server Development Guide

Degree of freedom: MIXED. Which tools to expose [HIGH freedom]; SDK tool shape, annotations, env-based auth, and Inspector [LOW freedom — run exactly].

Create MCP servers that enable LLMs to interact with external services.

How to reason

1. Observe — the real agent job (search, create, send), not the raw API catalog
2. Interpret — compose-from-primitives vs one workflow tool
3. Classify — prefixed action names, typed params, annotations (readOnly / destructive / idempotent)
4. Verify — Inspector + valid/invalid/edge; errors tell the agent what to do next

Worked example