Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so "changes nothing" largely restates structured data. The added "Free" supplies cost/pricing context not present in the annotations, but no return-format or polling-cadence detail is offered.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.