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

With no annotations, the description carries full responsibility. It discloses that data is read live from public RPCs, that the tool is paid via a two-step x402 flow, and that `tx_type` includes OP-stack L1 data fees. The payment mechanism is fully explained, ensuring the agent understands the cost and workflow before calling.

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 sentences, each with a distinct purpose: core function, optional mode, payment workflow, and free alternative. No fluff or repetition. The most critical information is front-loaded in the first sentence, and every clause earns its place.

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?

Despite having no output schema, the description explains both phases of the result: payment terms on the first call and data on the second. It covers live source, optional transaction costing, and the alternative `pricing` tool. For a tool with 5 optional parameters and no annotations, this is remarkably complete.

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 the baseline is 3. The description adds meaningful context by explaining that `tx_type` changes the output from raw fees to USD transaction cost and detailing the two-step `x_payment` flow. It does not need to repeat schema descriptions, so a 4 is appropriate for the added clarity.

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 explicitly states it reads live EIP-1559 fees for a single chain, with specific fee tiers and optional transaction-cost mode. It distinguishes itself from the `pricing` tool, which lists all prices, and from `gas_compare`, which likely compares chains. The verb 'read' and resource 'fees' are clear and specific.

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 provides explicit when-to-use guidance: 'Pass tx_type to get the USD cost of that specific transaction instead' and 'The free `pricing` tool lists every price at once.' It also explains the payment flow, telling users to call without `x_payment` to receive terms, then call again with it. This fully orients an agent toward correct invocation.

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