Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, so the description needn't rehash safety. It adds value by enumerating the elements stripped (headers, bold, italic, code fences, links, lists) and explaining the cost-reduction benefit, which goes 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.