Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=true, yet the description adds substantial context beyond them: no signing or transmission, the refusal behavior for write-sounding function names, and a precise pricing model ($0.002 USDC per successful call via x402 on Base/Solana/Arc, failed calls free). This is exactly the kind of cost and side-effect disclosure an agent needs before invoking a paid tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Four tight sentences, front-loaded with the core purpose then immediately the safety guarantee, the refusal rule, and the price. Every sentence carries distinct information — none is filler or restatement of the name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists to describe the decoded return value and annotations carry the safety profile, so the description only needed to cover semantics and cost — which it does fully. The refusal rule and per-call pricing close the remaining gaps an agent would face when deciding whether and how to call it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all four parameters (args, chain, contract, function) are already well documented in the schema, including the signature format and default chain. The description mirrors the function-signature example rather than adding format, syntax, or validation detail beyond what the schema supplies, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource — a read-only eth_call that decodes the return value of a named function — and sharpens it with a concrete example (balanceOf(address) returns (uint256)). It implicitly separates itself from write tools via 'nothing is signed or sent' but never names a sibling such as evm_simulate or evm_contract, so sibling differentiation is left to inference.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear context for use (calling view/pure functions and decoding their output) and an explicit exclusion rule: functions whose names read like writes are refused unless declared view or pure. It stops short of steering the agent to a specific alternative tool for those refused cases, so no named alternative is provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.