check_payment_signal

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

The description thoroughly discloses behavior beyond the annotations: real-money spend per uncached call, free cached/unknown responses, network and payment side effects, verification against published JWKS, and the caveat that the result is observational evidence, not a guarantee. This meaningfully enriches the annotation hints and contradicts nothing.

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 long, but almost every sentence earns its place given the unusual cost model and decision heuristic. It is front-loaded with the most critical information (SPENDS REAL MONEY) and organized from cost to functionality to usage to side effects. Slight over-density keeps it from a 5.

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 or nested object schema, the description explains what the tool returns (signed arispay.signal.v1 artifact with explicit freshness), how it is verified, the exact side effects, the caching behavior, and the usage threshold. This is complete enough for an agent to call it correctly and interpret its result.

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 schema already documents both parameters. The description reinforces that the resource must be the exact absolute HTTPS URL because evidence is keyed by that URL, but it does not add meaningfully new parameter-level semantics beyond what the schema states.

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 specific verb and resource: check_payment_signal buys and returns ArisPay Signal evidence about an x402 resource before payment. It clearly distinguishes this from siblings by framing it as a pre-payment verification step ('Use it BEFORE a material first payment') rather than the payment itself.

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 gives explicit when-to-use and when-not-to-use guidance: use before material first payments or after cached evidence expires, and skip when cumulative exposure is at or below the 1¢ check price. It also explains the decision denominator (cumulative exposure vs. cost of one failure) with a concrete example.

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