Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It transparently discloses the tool's behavior: it 'projects net yield' by combining live rates, gas costs, and historical returns. It also outlines information returned (position details, snapshot, cost breakdown, etc.). While it doesn't mention that this is a read-only operation or potential delays, the description gives a solid behavioral picture.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.