Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses that the tool is rejected by a read-only guard, implying a write/mutation operation and a potential failure mode. However, it does not describe success behavior, side effects, or required permissions. This is minimal but not entirely absent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.