Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Without annotations, the description carries the full burden. It discloses significant behavioral aspects: authentication via bearer token, cost per call, payment methods, window default (7 days), maximum (30 days), and the computation basis (hourly returns across nine chains). This goes beyond a basic purpose statement, though it omits details about output format or potential rate limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.