Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does disclose non-obvious data-handling behavior: grouping commas and currency symbols are parsed, and non-numeric rows are excluded but counted. This matters because the agent learns results may be computed over a subset. It does not cover permissions, failure modes, or the shape/ordering of the returned statistics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.