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x402 Challenge Payability and Payment Scheme Compatibility Check
x402
x402 Challenge Payability and Payment Scheme Compatibility Check is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status down (last checked 2026-10-23).
Returns a paid AI-generated decision procedure brief assessing whether an x402 challenge is payable and compatible with a given payment scheme, for autonomous agent use.
Price / call$0.002
Success—
StatusDown
How this service works
Paid agent-facing brief on x402 challenge payability and payment-scheme compatibility check: agent-side procedure that grades an incoming 402 challenge before any signature is attempted, verifying challenge version (v1 vs v2), network scheme (eip155: 8453, solana, xrpl, skale), whether the agent's wallet client has a registered scheme for that network, and price against spend caps. Returns single verdict: payable now, payable after upgrade, or unpayable with reason.. Blunt decision procedure,
Output
A JSON object containing a boolean success flag, payment confirmation, the service slug, provider name (K-2SO), and a result object with a human-readable prose decision procedure (120+ words), the topic, generation source (llm, reasoning, or deterministic), the model used, and an ISO-8601 generation timestamp.
Example use cases
Pre-flight x402 payability gate
“Before my agent tries to call a paid x402 API on Base, can you check whether the x402 challenge is actually payable and compatible with USDC settlement? I want the full decision procedure brief so I know what to expect.”
Debugging a failed 402 payment
“My autonomous agent got an HTTP 402 back from an x402 merchant and couldn't settle it — can you pull the payability and payment scheme compatibility decision procedure so I can figure out what went wrong?”
Onboarding a new x402 merchant integration
“I'm building an agent that will call x402 services and I need to understand if the payment scheme used by the merchant is compatible with my agent's setup — get me the decision procedure brief for x402 challenge payability and scheme compatibility.”
Technical details
Endpoint
GEThttps://k2so.wrong.systems/api/services/x402-challenge-payability-and-payment-scheme-com?utm_source=zero.xyzWhen to prefer
Choose this endpoint when an autonomous agent needs structured, authoritative guidance on whether a specific x402 HTTP 402 challenge can be paid and whether the payment scheme is compatible — particularly before attempting settlement or when debugging failed payments. Prefer it over generic documentation when you need a machine-readable, agent-optimized decision procedure with a prose brief that can be passed directly to an agent's reasoning layer.
Side effects
- HTTP 402 returned if payment has not been settled — agent must pay exact USDC amount and retry with PAYMENT-SIGNATURE header
- Invalid HTTP method (e.g. POST) returns an error — only GET, HEAD, DELETE accepted
- Malformed query parameters cause rejection
- Topic override ignored or misinterpreted if not a recognized x402 domain term
- LLM generation failure may fall back to deterministic source with reduced brief quality
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": "x402-challenge-payability-and-payment-scheme-com",
"procedure": "same as brief",
"generatedAt": "2026-01-01T00:00:00.000Z",
"generationSource": "deterministic"
},
"service": "x402-challenge-payability-and-payment-scheme-com",
"provider": "K-2SO"
}
}Tags
x402
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