Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With readOnlyHint and openWorldHint already covering the safety profile, the description adds a genuinely non-obvious behavioral caveat: on EVM chains only the first match is returned, so the reported chain may not be the intended one. That is real operational context the annotations cannot convey. It stops short of noting coverage gaps (e.g. untracked addresses) or rate limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.