Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden, and it does disclose useful preprocessing behavior: commas/currency are normalized and non-numeric rows are excluded and counted. It does not say what happens when the column is entirely non-numeric (error vs empty result), nor how nulls are treated, leaving meaningful gaps for a read-only analytics tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.