Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry the behavioral burden. It does disclose the core transformation: an inserted block group is converted into loose entities, which implies a mutating operation. However, it does not state whether the explosion is reversible, what happens to the original block definition or attributes, or whether specific permissions are required.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.