Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does disclose meaningful behavior: submitted data (SMILES, structures, results) is NEVER included, and api_key is used for rate limiting only. It does not state what happens after submission (confirmation, idempotency, whether the tool mutates server state), which is a modest gap for a write operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.