# Seller-Side Buyer Authority Verification Procedure

> 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.

## Facts

- Endpoint: GET https://k2so-8080.on.ascii.dev/api/services/agent-facing-decision-procedure-for-sellers-veri?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/seller-side-buyer-authority-verification-procedure-14112c18
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_BSlc-NlcRj-HFYrSORXJ8

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability seller-side-buyer-authority-verification-procedure-14112c18
```

Example prompt: I'm running a data seller service and a buyer agent just submitted an authority proof with a mandate, policy version, and settlement receipt — can you give me the step-by-step procedure to verify their authority claim and decide whether to serve the data, cap the response, ask for corrective proof, or refund and escalate?

## When to prefer this

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.

## Known failure modes

- 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

## 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.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Seller-Side Buyer Authority Verification Procedure paid response",
     "$schema": "https://json-schema.org/draft/2020-12/schema",
     "required": [
      "ok",
      "paid",
      "service",
      "provider",
      "result"
     ],
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "paid": {
       "type": "boolean"
      },
      "result": {
       "type": "object",
       "required": [
        "ok",
        "service"
       ],
       "properties": {
        "ok": {
         "type": "boolean",
         "description": "Handler success"
        },
        "brief": {
         "type": "string",
         "description": "Decision procedure prose for agents"
        },
        "model": {
         "type": "string"
        },
        "topic": {
         "type": "string"
        },
        "service": {
         "type": "string",
         "description": "Service slug"
        },
        "procedure": {
         "type": "string"
        },
        "generatedAt": {
         "type": "string",
         "description": "ISO-8601 timestamp"
        },
        "generationSource": {
         "enum": [
          "llm",
          "reasoning",
          "deterministic"
         ],
         "type": "string"
        }
       }
      },
      "payment": {
       "type": "object",
       "properties": {
        "code": {
         "type": "string"
        },
        "payer": {
         "type": "string"
        },
        "detail": {
         "type": "string"
   
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/seller-side-buyer-authority-verification-procedure-14112c18/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from k2so-8080.on.ascii.dev](https://www.zero.xyz/host/k2so-8080.on.ascii.dev/llms.txt)