Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, making the behavioral profile clear. The description adds value by specifying that the tool is a 'complete guide' and lists content areas, enhancing transparency about what data is returned beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.