Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish this as a read-only, non-destructive call. The description adds a key behavioral detail beyond annotations: 'Price: $0.001 USDC (x402)' indicates the call incurs a payment. It also specifies the data content (pool, taxes), enriching the behavioral picture. No contradiction with annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.