Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is fully covered by structured data. The description's added value is stating that the result includes the Pokemon that have the type, which tells the agent about response shape despite there being no output schema. It says nothing about lookup failure behavior for an invalid type.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.