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Pre-integration Merchant Challenge-Contract Grading for x402 Agents
x402
Pre-integration Merchant Challenge-Contract Grading for x402 Agents is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status down (last checked 2026-10-31).
Returns a deterministic decision brief that classifies a candidate paid API's 402 challenge quality and scores integration risk so an agent can decide to adopt, flag, or refuse the endpoint before committing payment.
Price / call$0.002
Success—
StatusDown
How this service works
Paid agent-facing brief on Pre-integration merchant challenge-contract grading for agents adopting paid x402 endpoints: a deterministic procedure to probe a candidate paid API without paying, classify its 402 challenge quality (proper 402 with price+network in WWW-Authenticate, wrong status 404/405/401, thin JSON, missing payment terms), score integration risk, and decide adopt/flag/refuse before wiring the endpoint into an-0. Blunt decision procedure, not marketing.
Output
A structured JSON response containing a decision procedure brief (prose), the challenge quality classification (proper 402, wrong status, thin JSON, missing payment terms), an integration risk score, and an adopt/flag/refuse recommendation — along with the generation source (llm, reasoning, or deterministic), service slug, and ISO-8601 timestamp.
Example use cases
Vetting a new paid data API
“I'm about to add a paid weather data endpoint to my agent stack — can you run the 402 challenge grading on it first and tell me if its payment contract looks solid or if I should flag it?”
Auditing a suspicious 404-returning endpoint
“This API I found keeps returning 404 instead of 402 when I try to access it without payment — can you classify what's wrong with its challenge contract and score the integration risk?”
Bulk pre-flight check before agent deployment
“Before I deploy my agent fleet to production, I need to grade the 402 challenge quality on our primary paid endpoint — run the deterministic decision procedure and tell me adopt, flag, or refuse.”
Technical details
Endpoint
GEThttps://k2so.wrong.systems/api/services/pre-integration-merchant-challenge-contract-grad?utm_source=zero.xyzWhen to prefer
Choose this endpoint when an AI agent needs a structured, deterministic pre-integration audit of a candidate paid x402 API — especially when the agent must decide adopt/flag/refuse before spending any USDC. It is specifically designed for the x402 ecosystem and understands WWW-Authenticate header conventions, price+network fields, and common malformation patterns that generic API testing tools would miss.
Side effects
- Candidate endpoint does not return any 402 response, making classification impossible
- WWW-Authenticate header is absent or malformed, causing thin-JSON or missing-terms classification
- Network or price fields are absent from the 402 challenge, resulting in a high-risk score
- Service unavailable on k2so.wrong.systems returns no brief
- Payment not completed results in unpaid 402 response from this endpoint itself
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": "pre-integration-merchant-challenge-contract-grad",
"procedure": "same as brief",
"generatedAt": "2026-01-01T00:00:00.000Z",
"generationSource": "deterministic"
},
"service": "pre-integration-merchant-challenge-contract-grad",
"provider": "K-2SO"
}
}Tags
x402
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