Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate readOnlyHint=false and destructiveHint=false, so the mutation is expected. The description adds valuable behavioral context: it explains automatic page handling (single-page auto-use, multi-page returns pages) and clarifies that the tool works for both reports and dashboards. This goes beyond what annotations provide, though it doesn't detail side effects like whether adding a section modifies the report irreversibly.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.