Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered; the description still adds value by stating 'no auth' and, more importantly, the provenance caveat that seeded listings are generated from public metadata and may be incomplete, with a pointer to the seller's live 402 challenge for exact prices. It stops short of rate limits or error behavior, but the data-reliability warning is a meaningful disclosure 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.