Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the safety bar is low; the description still adds real behavioral context beyond them — x402 pricing on Base ($0.02/call), a prepaid x-credit-token header for unlimited calls, 1 free call/day, and no API key required. It does not discuss latency, error modes, or multi-chain scope, keeping it short of a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.