Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations cover readOnly/destructive/openWorld, and the description adds real behavioral context: operator-session requirement, that the agent is operator-bound so no pairing PIN is needed, and the idempotencyKey retry semantics. The note that retrying the same key avoids a duplicate agent complements rather than contradicts idempotentHint=false, since the annotation correctly says the operation isn't inherently idempotent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.