Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, establishing a safe read operation. The description adds meaningful behavioral context by enumerating the specific fields returned (stake, entry time, earliness weight, payout) and emphasizing independent recomputability, which goes beyond the structured annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.