# Pre-Wallet Merchant Endpoint Vetting for x402 — K-2SO Decision Procedure

> Pre-Wallet Merchant Endpoint Vetting for x402 — K-2SO 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 2026-09-14).

Returns an LLM-generated decision procedure (plain prose brief) that guides an AI agent through vetting an x402 merchant endpoint before committing wallet funds to it.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/pre-wallet-merchant-endpoint-vetting-for-x402-a
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pre-wallet-merchant-endpoint-vetting-for-x402-k-2so-decision-procedure-b3cc9fc7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ht5kqeC3nSrNaDB5TZdXp

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 pre-wallet-merchant-endpoint-vetting-for-x402-k-2so-decision-procedure-b3cc9fc7
```

Example prompt: Before my agent pays any new x402 merchant endpoint, I want a decision procedure it can follow to vet the merchant — can you run the pre-wallet vetting procedure for an HTTP GET endpoint?

## When to prefer this

Choose this endpoint when an autonomous agent needs structured, LLM-generated guidance on whether to trust and pay a new x402 merchant endpoint — especially useful as a safety gate in agent wallets, agent marketplaces, or orchestration systems where new merchants are encountered dynamically. Prefer over manual rule sets when the agent needs nuanced, prose-form reasoning it can act on directly. Other K-2SO sibling endpoints cover quote comparison, refund windows, and allowlist governance; this one specifically focuses on the pre-payment vetting decision.

## 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 method enum value causes schema validation failure
- Topic override not recognized may result in generic procedure
- LLM generation failure may fall back to deterministic source
- Network timeout on the Base payment settlement step before retry

## How this service works

Paid agent-facing brief on Pre-wallet merchant endpoint vetting for x402: a decision procedure an agent runs before funding a wallet or first payment, to verify a merchant's x402/MPP endpoint is trustworthy. Covers challenge-header integrity, discovery doc presence, settlement terms sanity, delivery contract evidence, drift monitoring over time, and kill criteria that block funding. · Build a decision procedure or schema fo-0. Blunt decision procedure, not marketing.

## Output

A JSON object containing a plain-prose decision procedure brief (120+ words) advising an AI agent on how to vet an x402 merchant endpoint before paying, including the model used for generation, a timestamp, the generation source (llm/reasoning/deterministic), the service slug, and a payment confirmation object. The 'brief' and 'procedure' fields contain the actionable decision guidance.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Pre-wallet merchant endpoint vetting for x402: a decision procedure an paid response",
     "$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)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pre-wallet-merchant-endpoint-vetting-for-x402-k-2so-decision-procedure-b3cc9fc7/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)