Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety and idempotency are covered structurally. The description's one genuinely new behavioral fact is the World Bank as the data source and that only 'recent years' are returned, plus the accepted input forms; it says nothing about missing data, rate limits, or how gaps are handled.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.