Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Although annotations already declare readOnlyHint and idempotentHint, the description adds meaningful behavioral detail: the read is free, non-destructive, repeatable, does not refresh/re-evaluate/extend evidence, and fails without modifying the manifest on missing, expired, or mismatched credentials. This goes well beyond the annotations and does not contradict them.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.