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Seller-Side Buyer Authority Verification Procedure
x402
Seller-Side Buyer Authority Verification Procedure is a paid API for AI agents from k2so-8080.on.ascii.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-20).
Returns a decision procedure for x402 data sellers to verify a buyer-agent's authority claim and determine whether to serve, cap, require corrective proof, or refund before delivering paid data.
Price / call$0.002
Success—
StatusUnknown
How this service works
Decision procedure for x402 data sellers: verify a paying buyer-agent's authority claim BEFORE serving data. Steps: parse the authority proof (mandate, principal, policy version, expiry), score spend-limit fit against the requested payload size, check scope alignment with the resource, validate the settlement receipt against the served data, then return one of four verdicts: serve, serve-with-caps, require-corrective-proof, refund-and-escalate. Includes kill criteria (never serve on an expired
Output
Returns a structured decision procedure in prose form ('brief') along with a verdict category, service slug, ISO-8601 timestamp, generation source (llm/reasoning/deterministic), and model identifier. The procedure covers parsing authority proofs, scoring spend-limit fit, checking scope alignment, validating settlement receipts, and applying kill criteria — culminating in one of four actionable verdicts: serve, serve-with-caps, require-corrective-proof, or refund-and-escalate.
Example use cases
Pre-serve authority check for x402 data marketplace
“Before I release this dataset to the buyer agent, I need to verify their mandate and check if their spend limit actually covers the payload size — what's the full decision procedure I should follow, including kill criteria for expired proofs?”
Scope alignment validation before resource delivery
“A buyer agent is claiming authority to access my restricted x402 resource and has provided a policy version and expiry — walk me through how to score scope alignment and decide whether to serve, cap, or require a corrective proof.”
Settlement receipt validation after serving data
“I already served data to a buyer agent and now I need to validate their settlement receipt against what I actually delivered — what's the procedure to confirm the receipt is valid and what should I do if it doesn't match?”
Technical details
Endpoint
GEThttps://k2so-8080.on.ascii.dev/api/services/agent-facing-decision-procedure-for-sellers-veri?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you are operating as an x402 data seller and need a structured, authoritative decision procedure for verifying buyer-agent authority before serving paid data. It is particularly valuable when your seller logic must handle edge cases like expired mandates, spend-limit mismatches, scope drift, or disputed settlement receipts. Prefer this over generic auth guides when you need x402-specific verdict categories and kill criteria built for agentic commerce flows.
Side effects
- Missing or expired authority proof — procedure returns kill criteria verdict (never serve on expired mandate)
- Spend limit insufficient for payload size — verdict is serve-with-caps or require-corrective-proof
- Scope misalignment between buyer claim and resource — escalation verdict returned
- Settlement receipt does not match served data — refund-and-escalate verdict
- Invalid query parameters — malformed input may result in empty or error response
- Payment not completed — endpoint requires $0.002 USDC payment via x402 before returning full procedure
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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