Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description partially discloses behavior by listing modes (replace/add/remove) and the active parameter, implying selection state changes. However, it does not explicitly state side effects (e.g., whether the selection is replaced by default, or if other objects are deselected).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.