Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only say it is not read-only and not destructive; the description adds the important behavioral facts that this is a bulk, unfiltered action ('every') and that the effect is re-prompting on the next reveal. It does not mention confirmation or what is returned, but the core side effect is disclosed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.