# Seller-Side Paying-Agent Identity Verification Decision Procedure

> Seller-Side Paying-Agent Identity Verification Decision Procedure is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status down (last checked 2026-10-29).

Returns an LLM-generated decision procedure (prose brief) for how a seller-side autonomous agent should verify the identity of a paying agent in x402 transactions on Base.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/seller-side-paying-agent-identity-verification-d?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: down
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/seller-side-paying-agent-identity-verification-decision-procedure-5a96e41d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_a-r05K_k0TG6k5HnhS3TS

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-paying-agent-identity-verification-decision-procedure-5a96e41d
```

Example prompt: I'm building a seller-side agent merchant on Base that accepts USDC via x402 — give me a decision procedure for how my agent should verify the identity of a paying agent before or after settling a transaction.

## When to prefer this

Use this endpoint when an autonomous agent acting as a seller or merchant in an x402 ecosystem needs structured, LLM-generated procedural guidance on how to verify the identity of paying agents. Prefer this over generic identity verification guides when you need agent-native, x402-specific, Base/USDC-context-aware decision procedures delivered programmatically to an agent at runtime.

## Known failure modes

- HTTP 402 returned if payment has not been settled — agent must pay exact USDC amount and retry with PAYMENT-SIGNATURE header
- Payment signature mismatch or incorrect amount results in continued 402 rejection
- Network or provider downtime on k2so.wrong.systems returns 5xx errors
- Invalid query parameter values (e.g. unsupported meta value) may return 400
- LLM generation failure may result in ok:false with empty or null brief field

## How this service works

Paid agent-facing brief on Seller-side paying-agent identity verification decision procedure: when an x402 merchant must verify the agent that is paying them. Issuer-signed agent identity credentials (Ed25519 key binding, non-transferable tags), onchain agent IDs with task-history reputation scores, anonymous micro-payments vs identity-required purchases, reputation thresholds, revocation and key rotation handling, mismatch and impersonation response.-0. Blunt decision procedure, not marketing.

## Output

A JSON object containing a plain-prose decision procedure (120+ words) specifically about how a seller-side agent should verify the identity of a paying agent, including the topic, the model used to generate it, an ISO-8601 timestamp, the generation source (llm/reasoning/deterministic), and provider metadata from K-2SO. The 'brief' and 'procedure' fields contain the actionable guidance text.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Seller-side paying-agent identity verification decision procedure: whe paid response",
     "$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": {
         
… (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": "seller-side-paying-agent-identity-verification-d",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "seller-side-paying-agent-identity-verification-d",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/seller-side-paying-agent-identity-verification-decision-procedure-5a96e41d/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)