Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden; it does convey that results include contact counts, which is useful return-content context, and 'List' implies read-only. It omits pagination behavior, sorting, and any auth/rate-limit notes, so the behavioral picture is only partial.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.