Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral burden. It clearly conveys a read-only detection operation, but it does not disclose whether the tool returns a list, a boolean, or a report, nor what happens when duplicates are or are not found.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.