Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It usefully discloses metering ('Metered like the HTTP diff') and the possible result statuses, but never states whether the call is read-only or whether outcomes like OVERRIDE_RECEIPT or CONFIRMATION-REQUIRED cause writes, nor any auth requirements.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.