Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries much of the behavioral burden. It usefully discloses that results are citable, include id/title/url, and that the id can be passed to fetch. It does not mention potential result limits, pagination, ordering, or any rate/access considerations, leaving some behavioral uncertainty for a search operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.