Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open world), so the description's job is to add operational context — and it does, disclosing the hard 200-event ceiling and the visibility scope. It does not say whether results are newest-first or whether the 200 cap is a truncation with no pagination path, which would have completed the picture.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.