Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral disclosure burden. It usefully discloses that grouping commas and currency formats are handled and that non-numeric rows are excluded and counted. However, it does not clarify output structure, behavior on an empty or fully non-numeric column, or whether 'count' refers to valid numeric rows, excluded rows, or both.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.