Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations present, the description carries the full burden. It discloses that data is real-time, covers a 5m window, includes several specific metrics, and notes a $0.02 USDC cost. However, it does not disclose whether the tool is safe/read-only, what may cause failures, or any rate limits or token formatting requirements.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.