Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description goes well beyond annotations by disclosing output behavior (hosted download URL, 24-hour validity), usage limits (3 free demo renders/day), authentication expectations (Bearer tf_... key), and cost (25 units per render). This gives an agent a realistic model of side effects and requirements.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.