Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so description need not reiterate safety. The description adds value by detailing the output structure (description, steps, pros/cons, rank) and the canonical nature of methods, which helps the agent understand what to expect.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.