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Live Paid-Endpoint Response-Contract Failure Index for x402 and MPP Merchants
x402
Live Paid-Endpoint Response-Contract Failure Index for x402 and MPP Merchants is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status down (last checked 2026-10-19).
Returns a verdict on whether a specific x402 or MPP merchant endpoint correctly fulfills its paid-access contract, classifying failures as dead routes, contract mismatches, or thin-body content debt.
Price / call$0.002
Success—
StatusDown
How this service works
Live response-contract failure index: which x402 and MPP merchants advertise paid access but break the request contract. Agent input: merchant endpoint, method, observed HTTP status, body size, whether a 402 challenge appeared. Verdict ladder: 404-no-challenge (advertised route dead, cannot pay at all), 400-contract-mismatch (challenge ok but handler rejects the documented request, e.g. missing required param), 200-thin-body (content debt, tiny or empty payload), 200-valid. Includes the
Output
A JSON object containing a boolean success flag, payment confirmation, a verdict classification (404-no-challenge, 400-contract-mismatch, 200-thin-body, or 200-valid), a prose decision procedure of 120+ words explaining the verdict, the model used, a timestamp, and generation source (llm, reasoning, or deterministic).
Example use cases
Diagnosing a dead x402 merchant route
“I tried to pay to access an x402 endpoint at a merchant but I'm getting a 404 with no 402 challenge showing up at all — can you check if that route is simply dead and can't be paid?”
Catching content debt on a paid API
“A merchant's x402 endpoint is accepting payment and returning 200, but the response body seems almost empty — can you verify whether this counts as content debt and flag it as a thin-body failure?”
Auditing contract mismatch after 400 error
“I'm getting a 400 error from an MPP merchant's paid endpoint even though the 402 challenge looks fine — can you diagnose whether this is a contract mismatch where the handler is rejecting my documented request?”
Technical details
Endpoint
GEThttps://k2so.wrong.systems/api/services/live-paid-endpoint-response-contract-failure-ind?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to systematically audit whether x402 or MPP merchant endpoints are genuinely delivering on their paid-access promises — especially before routing agent payments to a new merchant, after observing anomalous payment outcomes, or when building a compliance index of merchant endpoint health. Prefer it over generic HTTP testing tools because it applies the specific x402/MPP verdict ladder and produces agent-readable prose rationale.
Side effects
- Missing required 'type' or 'method' fields returns a 400 contract error
- Invalid method value outside GET/HEAD/DELETE enum causes validation failure
- Payment not completed results in a 402 challenge response rather than verdict
- Merchant endpoint unreachable causes upstream timeout or error
- Empty or malformed merchant input leads to indeterminate verdict
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"paid": true,
"result": {
"ok": true,
"brief": "plain prose decision procedure (120+ words)",
"model": "deepseek/deepseek-v4-flash-0731",
"topic": "string topic",
"service": "live-paid-endpoint-response-contract-failure-ind",
"procedure": "same as brief",
"generatedAt": "2026-01-01T00:00:00.000Z",
"generationSource": "deterministic"
},
"service": "live-paid-endpoint-response-contract-failure-ind",
"provider": "K-2SO"
}
}Tags
x402
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