Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already supply readOnlyHint=true and destructiveHint=false, so the description's burden is lighter. It adds value by disclosing that the output states default legal rules rather than predicting actual estate devolution, and by listing the specific questions the tool addresses. This is honest, useful behavioral context beyond the structured annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.