Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint, idempotentHint, and openWorldHint. Description adds authentication details (session ID, no API key arguments), session type explanation, and operational constraints (TRX only, min 10 TRX). 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.