Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, yet the description still adds real behavioral context: a 20 calls/hour rate limit, the four upstream exchanges, the top-200 coin universe, and the explicit absence of line values. It stops short of saying what happens when the rate limit is hit, but the added context is well beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.