Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does add real behavioral detail: grouping commas and currency are handled, non-numeric rows are excluded and counted. However, it omits error behavior (what happens for a non-numeric or unknown column), output shape, and any performance/read-only framing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.