Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It meaningfully discloses edge-case handling: grouping commas and currency symbols are parsed, and non-numeric rows are excluded and counted. It does not mention return format or error behavior, but for a simple stats tool these disclosures are strong.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.