# K-2SO Seller-Side Buyer Authority Verification Decision Procedure

> K-2SO Seller-Side Buyer Authority Verification Decision Procedure is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-30).

Returns a paid LLM-generated decision procedure (prose brief) for agents verifying buyer authority on the seller side of an x402 transaction

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/agent-facing-decision-procedure-for-sellers-veri?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/k-2so-seller-side-buyer-authority-verification-decision-procedure-c24214f7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_iHK7f8eTxIv08S4mSg0SS

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 k-2so-seller-side-buyer-authority-verification-decision-procedure-c24214f7
```

Example prompt: I'm building an autonomous merchant agent on Base and need a decision procedure for verifying that a buyer actually has authority to make a purchase — can you pull the seller-side buyer authority verification brief from K-2SO?

## When to prefer this

Choose this endpoint when an autonomous agent acting as a seller in an x402 micropayment flow needs a ready-made, LLM-generated decision procedure for verifying buyer authority — particularly when the agent lacks its own compliance or policy logic and needs an external brief to act on. Prefer over generic LLM prompting when you want a structured, versioned, paid procedure with provenance metadata (model, timestamp, source).

## Known failure modes

- HTTP 402 returned if payment has not been settled — agent must pay exact USDC amount and retry with PAYMENT-SIGNATURE header
- Invalid or missing method enum value causes schema validation failure
- Topic override ignored or misinterpreted if not a clear natural-language string
- Stale or cached generation if generationSource returns 'deterministic' rather than 'llm'
- Network or provider downtime on k2so.wrong.systems results in no response

## 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

A JSON object containing a plain-prose decision procedure brief (120+ words) for seller-side buyer authority verification, the model that generated it (e.g. deepseek/deepseek-v4-flash-0731), a generation source label (llm/reasoning/deterministic), an ISO-8601 timestamp, the service slug, and provider attribution from K-2SO. Payment metadata (payer address, transaction hash) is also included when paid.

## 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)
```

## Response schema (JSON Schema)

```json
{
 "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": "agent-facing-decision-procedure-for-sellers-veri",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "agent-facing-decision-procedure-for-sellers-veri",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/k-2so-seller-side-buyer-authority-verification-decision-procedure-c24214f7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from k2so.wrong.systems](https://www.zero.xyz/host/k2so.wrong.systems/llms.txt)