Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations (readOnlyHint, openWorldHint, idempotentHint, destructiveHint) already indicate a safe, read-only, and idempotent tool. The description adds that encouragement is not sincere, but does not elaborate on behavioral traits like output format or statelessness. With strong annotations, the description adds minimal value.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.