Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations provide no safety hints beyond all false (not read-only, not idempotent, not destructive). The description adds the purpose of preventing fabrication, which is a behavioral reason. However, it does not disclose any side effects, such as whether it creates a new record or modifies existing state, or any confirmation or return behavior. Since annotations carry no safety profile, the description could do more.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.