Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark readOnly and non-destructive, so the description correctly doesn't repeat those. It adds useful context: facts come from 'Savvly's own current records' and the response includes primary sources (e.g., SEC filings). This informs the agent about data currency and reference material, going beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.