Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. Beyond that the description adds nothing: no dimension-compatibility requirement, no behavior for invalid shapes, no note on size limits (maxItems 10000) or computational cost. The '(A × B)' ordering is the only added detail.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.