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

With no annotations, the description carries the full burden and does so well: it discloses supported chains, the exact estimation method, fallback behavior, fee tiers, L1 data fee on OP-stack chains, USD conversion via Chainlink, revert reporting instead of failure, and the $0.002 USDC x402 cost. It also provides a concrete output example, making behavior fully transparent.

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?

The description is front-loaded with the core purpose and usage, then layers on behavioral details and an example. It is appropriately sized for a multi-chain fee tool, though the example output is truncated mid-JSON, which slightly undercuts its value.

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?

Given five optional parameters, no annotations, and no output schema, the description is complete enough for an agent to call the tool correctly. It covers chains, inputs, fallback behavior, fee components, error handling, cost, and return shape via the example.

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 the baseline is 3. The description reinforces the meaning of 'to, from, value, data' and the no-'to' plain transfer case, but it does not add syntax, format, or constraints beyond what the schema already documents.

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?

The description states a precise verb and resource: 'Gas estimate and fee quote' across five named chains. It specifies the exact method (eth_estimateGas) and the fallback behavior (plain transfer if no 'to'), so an agent knows exactly what the tool does without opening the schema.

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?

It gives explicit usage guidance: 'Use before signing or to budget agent transactions.' This tells the agent when to invoke it. It does not name alternatives or when-not to use it, but no sibling tool overlaps in function, so the condition is clear enough.

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