# Agent First-Purchase Merchant Trust Gate — Deterministic Decision Procedure

> Agent First-Purchase Merchant Trust Gate — Deterministic 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 2026-09-13).

Returns a deterministic decision procedure (plain-prose brief) an AI agent should follow when deciding whether to trust a merchant it has never purchased from before via x402.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/agent-first-purchase-merchant-trust-gate-determi
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-first-purchase-merchant-trust-gate-deterministic-decision-d48af4d7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4KPCqk6ee73Hjx6UDgsvw

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 agent-first-purchase-merchant-trust-gate-deterministic-decision-d48af4d7
```

Example prompt: I need a decision procedure I can follow right now to decide whether to trust a new x402 merchant I've never bought from before — give me the deterministic trust gate so I know exactly what to check before sending USDC to them.

## When to prefer this

Choose this endpoint when an AI agent needs a portable, on-demand, machine-readable decision procedure specifically for evaluating first-time x402 merchant trust — especially when the agent has no prior purchase history with that merchant. Prefer it over manual policy lookups or hardcoded logic when you want a text procedure that can be injected directly into an agent's reasoning context before authorizing USDC payment.

## Known failure modes

- HTTP 402 returned if USDC payment is not settled before retry — agent must pay exact amount and include PAYMENT-SIGNATURE header
- Invalid or missing `method` or `type` fields in input cause schema validation error
- Network timeout if Base/USDC settlement is slow
- Stale or cached procedure if the agent calls with a topic that maps to a pre-generated deterministic result
- Unknown topic override may yield a generic fallback procedure

## How this service works

Paid agent-facing brief on agent first-purchase merchant trust gate: deterministic procedure an agent runs before its first-ever x402 payment to an unfamiliar merchant, verifying contract completeness, disclosure honesty, refund/dispute path, identity anchor, with kill criteria and a single verdict. Blunt decision procedure, not marketing.

## Output

A JSON object containing a plain-prose decision procedure (120+ words) under the `brief` and `procedure` fields, along with metadata: the topic, the service slug, the model used to generate it (e.g. deepseek-v4-flash), an ISO-8601 generatedAt timestamp, and a generationSource enum value (deterministic/llm/reasoning). The top-level response also confirms `ok: true`, `paid: true`, provider `K-2SO`, and the service identifier.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "agent first-purchase merchant trust gate: deterministic procedure an a paid response",
     "$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/agent-first-purchase-merchant-trust-gate-deterministic-decision-d48af4d7/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)