Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description goes beyond this by disclosing the 50-record cap and the exact fields excluded (message body, preview, message id, etc.), giving the agent a precise, honest behavioral contract. No contradiction with annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.