Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It discloses that the tool is free, that behavior depends on whether the block is claimed or unclaimed, and exactly what information is returned in each case. It does not mention error behavior, but the schema covers coordinate validation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.