Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses that the data is empirical ('observed in the wild'), includes counts, and is not an invented specification. This is meaningful behavioral context for a zero-parameter reference tool. It doesn't describe return formatting, but the scope is simple enough that the description adds adequate transparency.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.