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Merchant Discovery Surface Verification Standard
x402
Merchant Discovery Surface Verification Standard is a paid API for AI agents from k2so-8080.on.ascii.dev, paid per call via x402, $0.012/call, status unknown (last checked 2026-09-15).
Verifies consistency and authenticity of a merchant's five agent discovery surfaces (agent.json, llms.txt, x402 payment meta, A2A agent card, plugin manifest) before authorizing payment.
Price / call$0.012
Success—
StatusUnknown
How this service works
Deterministic pre-payment procedure for verifying a merchant's agent discovery surfaces (well-known/agent.json, llms.txt, x402 payment meta, A2A agent card, plugin manifest). Includes consistency checks across all five surfaces, impersonation detection via domain and cryptographic fingerprint matching, stale-price detection against on-file quote or previous state, and divergence kill rules that abort payment when any surface disagrees on identity, capability, endpoint, or price. Returns a PASS,
Output
Returns a PASS or FAIL verdict along with a decision-procedure prose brief for agents, a service slug, generation source (llm, reasoning, or deterministic), ISO-8601 timestamp, and payment metadata including payer, transaction ID, and self-pay flag. The 'ok' boolean indicates handler success and the 'brief' field provides actionable prose explaining the decision.
Example use cases
Pre-payment impersonation check
“I'm about to send 5 USDC to this merchant agent — can you first verify all five of their discovery surfaces and make sure the domain fingerprint actually matches what's on file? Abort if anything looks like impersonation.”
Stale price detection before checkout
“The merchant quoted me a price earlier but I want to make sure their x402 payment meta and agent card still agree on that price before I authorize the transaction — run the surface verification and let me know if the price has drifted.”
Discovery surface consistency audit
“Can you audit this merchant's agent discovery setup — check that their agent.json, llms.txt, A2A card, plugin manifest, and x402 meta are all consistent with each other on identity, capabilities, and endpoint, and give me a PASS or FAIL?”
Technical details
Endpoint
GEThttps://k2so-8080.on.ascii.dev/api/services/agent-discovery-surface-verification-standardWhen to prefer
Use this endpoint when an AI agent is about to execute an x402 payment to a merchant and needs a deterministic, multi-surface pre-payment safety check. Prefer this over single-surface checks or manual inspection when operating autonomously and when the risk of impersonation, stale pricing, or surface divergence is non-trivial. Especially valuable in high-frequency agentic payment workflows where human oversight is absent.
Side effects
- Surface disagreement on identity, capability, endpoint, or price triggers a divergence kill rule and returns FAIL
- Cryptographic fingerprint mismatch causes impersonation flag and payment abort
- Stale price detected against on-file quote returns FAIL with stale-price detail
- Network timeout or unreachable discovery surface URL causes handler error
- Missing or malformed discovery surface documents cause validation failure
- Payment not included returns 402 with x402 payment required headers
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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