Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden for behavioral disclosure. It adds valuable detail about units ('Balance is in satoshis for BTC wallet and cents for USD wallet'), which goes beyond the basic function and helps the agent interpret results correctly. No mention of read-only safety, but 'Get' implies a read operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.