Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the tool as read-only, idempotent, and non-destructive, so the description doesn't need to restate that. It adds the fact that output is factored form, but does not discuss edge cases like non-factorable polynomials or coefficient domains, which is a minor gap.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.