Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so safety is covered, but the description adds nothing beyond the action itself. It doesn't say whether the scroll waits for lazy-loaded content, whether it pages in one jump or incrementally, or whether any state/result is returned. For a browser-automation tool, those are the traits an agent needs.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.