Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations provide no safety profile (all hints false), so the description carries the full burden. It does disclose cost ($0.50/call), compliance constraints, and the JSON result shape, which is useful. But it does not state whether the call has side effects, requires auth, or has rate limits, leaving mutability ambiguous.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.