Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, non-destructive, closed-world behavior, so the bar is lower; the description still adds real value by defining the result shape and the 'not_checked' sentinel for never-reviewed creatives. It does not say what happens if compliance is unavailable for the workspace or whether failed checks are paginated/truncated.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.