Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses that grouping commas and currency are handled, and that non-numeric rows are excluded and counted. This is useful behavioral context beyond the schema. However, it does not mention whether the tool returns a single object or a list, or whether it errors on an empty column, so it is not a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.