Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds value by listing the specific fields returned (customer, tier, billing cycle, renewal info), giving the agent a clearer picture of the behavior beyond what annotations convey. No contradictions.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.