Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, but it does disclose a genuinely useful trait: this is an eth_call, i.e. a read-only simulation with no gas cost, signing, or state mutation. That is real value. It stops short of stating which chain/network is queried, whether the read reflects finalized state, or what happens for a missing commitment.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.