Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations supplied, the description carries the full burden, and it does disclose the key trait: the message is transient and non-intrusive ("short floating") on the canvas rather than a modal or a document change. It does not say whether the call blocks, whether the user must acknowledge it, or what happens if a notification is already displayed, which leaves real behavioral gaps for an unannotated tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.