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 add non-obvious value: grouping commas and currency symbols are parsed, and non-numeric rows are excluded yet counted. However, it omits what happens if the column is entirely non-numeric, whether errors are raised, and how the excluded-row count is surfaced in a response with no output schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.