Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds valuable context beyond these: no authentication required, open CDC/CMU Delphi data, unlimited free access, and the dimensional breakdown of the returned rates. It does not contradict the annotations, and missing pagination/rate-limit details are less critical given the output schema exists.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.