Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already disclose write, non-idempotent, non-destructive, and open-world behavior. The description adds critical context beyond that: the server cannot sign, the signature must be made externally, and the signed payload is the RFC 8785 (JCS) form of {body, handle, parent, ts}.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.