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

Annotations cover the safety profile (readOnlyHint, destructiveHint false, idempotentHint false), and the description adds meaningful context beyond them: reverting transactions return 422 with a reason and are uncharged, each call is billed ($0.01 via x402 USDC or card key, first 25 free, failed calls free), and repeats are not free. That billing/idempotency detail is exactly what an agent needs before retry loops.

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?

Purpose and scope are front-loaded, then inputs, then use cases, then pricing. It is dense but nearly every clause carries information; the final sentence bundles the read-only claim with billing and repeat-charge caveats and could be split for readability.

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?

No output schema exists, so the description compensates by naming the return units (gas units, gwei, HYPE) and the failure mode (422 with revert reason, uncharged). For a read-only estimation tool with a fully documented schema, nothing an agent needs to call it correctly is missing.

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 coverage is 100%, so baseline is 3; the description still adds routing semantics by saying 'from' is needed 'when the call depends on it' and that 'value' is denominated in HYPE, plus a concrete example address. It doesn't add format details beyond the schema, so it isn't a 5.

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 ('Estimate the gas a transaction would use on HyperEVM (eth_estimateGas)') and explicitly names what it also returns: gas units, gwei, and HYPE cost. It distinguishes itself from hyperevm_gas by scoping that sibling to 'the gas price alone'.

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 explicit when-to-use ('before sending a transaction or to price a batch') and an explicit alternative with its selection condition ('for the gas price alone use hyperevm_gas'). It also names which inputs to supply for a contract call versus a plain transfer.

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