Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already disclose that this mutates state (readOnlyHint=false), is idempotent, and is non-destructive, so the description is not required to carry the full safety burden. It nonetheless adds nothing: it does not clarify what 'reset' means (to zero, or clearing the unread flag), whether the operation is scoped to the caller, or whether reset is recoverable.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.