Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description does add genuine behavioral context beyond them: fields related to unauthorized resources are masked in the response, which affects how the agent should interpret the payload. However, it does not say how masking is determined or whether it can vary per caller.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.