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

With no annotations, the description carries the burden and does disclose two important traits: the call costs $0.005 paid over x402, and passing the payment parameter completes the purchase inside the tool call. It does not state whether the diagnosis itself can incur external calls, whether failures cost anything, or any read-only guarantee, so it falls short of full disclosure.

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 tight sentences, front-loaded with the core diagnostic question and then the concrete checks performed, with the pricing disclosure appended. 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?

With no annotations and no output schema, the description must supply the operational picture, and it does: what it inspects, what it returns (each problem with its fix), and the cost model. It leaves some ambiguity about when the $0.005 is charged and how payment interacts with a diagnosis-only run.

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 schema already documents url, method, and payment. The description's note about the PAYMENT-SIGNATURE payload elaborates on the payment parameter but largely restates the schema, so baseline 3 applies.

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 precise diagnostic purpose: determine why Coinbase won't list an x402 endpoint and whether a standard client can pay it. The enumerated actions (read the 402 like a client, check facilitator/Bazaar enforcement, ask Coinbase's validator) make it clearly distinct from siblings like x402_inspect or x402_payment_test.

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?

Usage is implied by the diagnostic scenario, but there is no explicit when-to-use/when-not guidance and no routing to alternatives such as x402_inspect, x402_seller_check, or x402_payment_test despite heavy sibling overlap. An agent can infer intent from the problem framing but is not told which tool to pick.

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