Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish read-only/idempotent safety, but the description adds materially: the simulation method, explicit uncertainty, rolling-origin diagnostics, 'no invented data' sourcing, and a $1.00 per-call cost. That pricing and data-provenance detail goes well beyond annotations, though latency and request limits are unstated.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.