Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, and non-destructive behavior, so the description adds useful behavioral context beyond them: the result order ('newest first') and the inclusion of causal information. This is meaningful, though it does not detail the full return payload shape.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.