Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only/idempotent/non-destructive/open-world, so the bar is lower. The description adds real value beyond them: the computation method (zero-address mints+burns over a window, annualised vs live totalSupply), the 'rate not intent' caveat, and access/pricing behavior ($0.03 x402, prepaid header, 1 free/day, no key).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.