Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare a non-read-only, non-destructive write. The description adds genuinely useful behavioral context beyond that: a human reads every report, no key is required, and an optional key links the report to the account. It doesn't cover reversibility or turnaround, but the auth and human-review disclosures are meaningful additions.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.