Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already carry readOnly/idempotent/non-destructive, so the description's job is to add data-quality context, which it does well: EPS is not normalized, past estimate revisions are unavailable, missing source rows/provenance are reported rather than filled, and consensus is capped at three future fiscal years. These are exactly the caveats an agent needs to avoid overclaiming, though it stops short of describing scale or latency behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.