Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false. The description adds real value beyond that by disclosing the downstream consequence: generated PDFs will stop including the company logo. It stops short of saying whether the old logo asset is recoverable or whether any error occurs when there is no logo.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.