Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries full behavioral burden. It does disclose that this is a full-text search and that it returns passages themselves, implying a read-only operation. But it does not mention match semantics, sorting, pagination, authentication needs, or rate limits, which are relevant for a search tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.