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

With no annotations, the description does real work: it discloses that this is a paid call ($0.01 USDC on Base/eip155:8453), where the payment must be placed (params._meta['x402/payment']), the HTTP endpoint, and the shape of the result. It does not disclose behavior when neither optional parameter is supplied, which is a notable gap given zero required parameters.

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?

Front-loaded and readable, but the pricing is stated twice ('$0.01/call' and 'Price: $0.01 per call in USDC on Base'), which wastes space. The HTTP endpoint and payment mechanics are appended in a dense run-on rather than structured.

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?

For a two-parameter, no-output-schema tool, the description covers inputs, matching method, return fields, and payment requirements. What remains missing is the handling of the zero-parameter case and a clearer definition of 'consolidated lists', but an agent can otherwise invoke it correctly.

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 two parameters are already fully documented. The description adds only marginal meaning beyond the schema, namely that name matching is fuzzy and that address is screened 'instead of' a name, hinting at mutual exclusivity without stating it explicitly.

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 resources: screening a company name or EVM wallet address against OFAC SDN and consolidated lists with fuzzy matching, plus what it returns. It is clear on its own, but never names or distinguishes itself from close siblings such as x402check__address, x402check__check, or check_sanctions__screen, so an agent still has to guess which screening tool to pick.

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?

There is no when-to-use guidance at all: no mention of when to prefer this over the sibling screeners, no prerequisites, and no exclusions. The only routing hint ('instead of a name') is about parameter choice, not tool choice, and is already implied by the schema.

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