Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description only needs to add context. It does: it discloses that the read happens on-chain and that the result includes a behavioral ERC-20 conformance check, which is a real semantic beyond the annotations. It does not describe behavior on invalid/non-ERC-20 addresses, but the bar is lower given annotation coverage.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.