Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Goes well past the annotations: pay-per-call with no API key, price computed from max_tokens, unused tokens not refunded, 20s server timeout with no charge if it fires, and a recommended 30s client timeout. An agent learns the cost and failure model before calling, which the readOnly/openWorld/idempotent hints do not convey.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.