Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and idempotentHint, so the description doesn't need to restate those. It adds a bit beyond annotations by noting bulk support and that transcripts are 'previously generated', but doesn't disclose potential errors or response characteristics, so some behavioral context is missing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.