Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does so well: it discloses auth/payment requirements (API key or 2 cents via Binance b402/x402), that exchangeTouching is null on bitcoin/tron/sui, that the solana row returns null, and the window bounds (default 24, max 168). It stops short of describing pagination, rate limits, or output shape, but the coverage/null semantics are unusually explicit.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.