
Tool Annotations as Risk Vocabulary: What Hints Can and Can't Do
The MCP team reviews the state of tool annotations — the metadata that tells clients whether a tool is read-only, destructive, or reaches outside its local environment. Five community SEPs have proposed new annotations, and this post provides a clear framework for evaluating them: what annotations can actually communicate, where the limits are, and how clients should treat them as hints rather than guarantees. Essential reading for MCP server developers.