Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description must carry the behavioral transparency burden. It only says 'Save,' which implies a persistence/write operation, but it does not disclose whether the current file is overwritten, whether project_name triggers a save-as behavior, or what happens when project_name is null.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.