Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly=true, idempotent=true, non-destructive. The description adds material context beyond that: the tool is paid (0.02 USDC per call) via x402 on five named chains, which is critical invocation info an agent cannot get from annotations. It also discloses the data composition (venue share, long/short split, biggest print).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.