Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and openWorldHint, so the description's job is to add context — which it does by enumerating the result fields (accession, study type, samples, platforms, linked PMIDs). It doesn't disclose corpus size, rate limits, or result ordering, but the essential behavioral shape is conveyed without contradicting the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.