Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, not destructive, closed-world), and the description adds substantial context beyond them: local heuristics (no external calls), a free sample plus paid URL/pay steps, and the exact cost ($0.35 Base USDC via x402). That payment and sample/full distinction is behavior an agent cannot derive from annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.