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

With no annotations, the description carries the full behavioral burden and does disclose two important traits: data provenance ('from real receipts') and the payment model ('$0.001 per call over x402'). It leaves out things like rate limits or failure behavior, but the cost/payment disclosure is meaningful context beyond the schema.

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?

Two sentences, zero waste: the measurement and its coverage come first, the billing model second. Everything is front-loaded.

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 or annotations exist, so the description must describe the return: it says the result is a dollar cost with the L1 data fee included across three transaction types, which is most of what an agent needs. It doesn't specify the exact shape (e.g., per-type breakdown), a minor gap.

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?

Only one parameter and schema coverage is 100%, so the schema already fully documents the x402 payment payload. The description adds nothing about the parameter itself, which is acceptable given the schema does the work.

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?

Names the specific resource (transaction cost on Base) and enumerates the covered transaction types (ETH transfer, USDC transfer, Uniswap swap) with the inclusion of the L1 data fee. This is specific enough to separate it from the sibling arc_gas, which covers a different chain.

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?

The description implies usage (getting current real-world gas cost in dollars) but never states when to pick this over arc_gas or how to interpret it for a cost decision. The per-call pricing note gives billing context, not selection guidance.

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