Glossary · Phase 9 · Model Context Protocol
Tool annotations
Hints a server attaches to a tool, such as read-only or destructive. They're the server's own claims, so only trust them from trusted servers.
Try it now
Tool errors are written for the model, so it can correct itself.
Learn it properly
Build a server: tools · Tool definitions, schemas from type hints, results and two kinds of error. About 45 minutes.
Never trained an AI?
Teach a small one to write, right in your browser. It takes about 20 seconds and needs no account.