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

With no annotations, the description carries the burden and does well: it discloses the cost ($0.005 per call), the payment/auth rail (x402 USDC), and the underlying method (eth_estimateGas), and implicitly confirms nothing is signed. It does not disclose return shape or revert-error behavior, which keeps it from a 5.

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?

Three compact sentences with the core capability front-loaded, then the cost/payment mechanism. Every sentence earns its place with no filler.

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?

For a read-only estimation tool with no annotations and no output schema, the description covers purpose, cost, and rails, and implies the return (gas estimate plus price). It could say more about what a revert response looks like, but it is otherwise sufficient.

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 five parameters (to, data, from, chain, value) are already documented in the schema. The description adds no format or semantic detail beyond what the schema provides, making the baseline 3 correct.

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+resource ('Estimates the gas a transaction would need') and adds scope ('before you sign anything', 'find out that a call would revert') that separates it from evm_gas and evm_call without naming them. The purpose is unambiguous, though explicit sibling naming would push this to a 5.

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?

'before you sign anything' and 'cheapest way to find out that a call would revert' give clear when-to-use context. No alternatives (e.g. evm_call or evm_fees) are named, and there are no when-not cases, so it stops short of a 5.

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