Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden, but it only states that a server is generated. It does not disclose whether files are scaffolded into the directory, whether anything is overwritten, whether an api_key is used in the generated output, or what artifacts result.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.