Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish read-only, idempotent, non-destructive behavior. The description adds important behavioral context beyond annotations: the call costs 0.003 USDC via x402 on Solana or Base, and the data is described as a 'complete unthrottled tape' covering all recorded USDT perps. This is genuinely useful operational information.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.