Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=false, non-idempotent), and the description adds a genuinely non-obvious behavioral caveat that the annotations cannot express: incoming content arrives as literal plain text with ** and # preserved verbatim.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.