Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and destructiveHint=false, so safety is covered. The description adds no behavioral context of its own: it doesn't say whether text is visible-only, whether hidden/script text is included, whether output is truncated, or that results reflect the current DOM state after scrolling/waiting.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.