Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the readOnly/openWorld annotations, it discloses the pricing model ($0.002 USDC per successful call via x402 on Base, Solana or Arc), that failed calls are not charged, and that data freshness trails publication. These are exactly the operational facts an agent needs and cannot get from structured fields.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.