Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the description doesn't need to restate safety. It adds valuable behavioral context: the include_data_quality=true option triggers an extra set-history scan and yields a data_quality block, and it explains what that block contains (e1RM coverage, fragmented variants, etc.). This goes beyond the annotation and helps the agent anticipate cost and output shape.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.