# Nomos Merchant Trust Assessment

> Nomos Merchant Trust Assessment is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.2/call, status unknown (last checked 2026-09-15).

Evaluates the risk and trustworthiness of a merchant for a given payment or transaction context, returning a risk score, risk level, and flags.

## Facts

- Endpoint: POST https://base-agent-preflight.bytoken2023.workers.dev/x402/v1/merchant/trust
- Price: $0.2/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/nomos-merchant-trust-assessment-c30c3d6d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ovczqwmLo0070BmPvAbl1

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 nomos-merchant-trust-assessment-c30c3d6d -d '<json body>'
```

Example prompt: Before my agent pays 50 USDC to merchant ID 'acme-store-001' from origin 'https://acme.store' for 'software subscription', can you run a Nomos merchant trust assessment and tell me the risk level and any flags?

## When to prefer this

Use this endpoint when an autonomous agent needs a fast, pay-per-request preflight trust signal for a specific merchant before executing a USDC payment on Base. Prefer it over generic fraud APIs when you need blockchain-native risk scoring tied to merchant identity and on-chain provenance, and when operating in agentic pipelines that already use x402 micropayment infrastructure.

## Known failure modes

- Missing required query params (merchant_id, origin, amount_usdc, purpose) returns a 400 validation error
- Invalid amount_usdc format (non-numeric or wrong precision) causes schema rejection
- Payment of 0.2 USDC required via x402 protocol; missing or failed payment returns 402
- Unknown merchant_id with no data may return risk_level 'unknown' with zero score and no flags
- Network or Cloudflare Worker outage returns 5xx; retry with idempotency_key to avoid double-charge

## How this service works

Machine-payable service intelligence for discovering, verifying, and monitoring identity, risk, authorization, execution-preflight, and evidence APIs before autonomous agents spend.

## Output

Returns a JSON object with the network (e.g. 'eip155:8453' for Base), product name ('nomos-merchant-trust'), and an assessment object containing risk_level ('low', 'medium', or 'high'), a numeric risk_score, and a flags array listing any specific risk signals. May also include identity, activity, and provenance sub-objects with enriched merchant context.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "merchant_id",
      "origin",
      "amount_usdc",
      "purpose"
     ],
     "properties": {
      "origin": {
       "type": "string",
       "maxLength": 500,
       "minLength": 8
      },
      "wallet": {
       "type": "string",
       "maxLength": 120,
       "minLength": 26
      },
      "purpose": {
       "type": "string",
       "maxLength": 120,
       "minLength": 2
      },
      "amount_usdc": {
       "type": "string",
       "pattern": "^[0-9]+(?:\\.[0-9]{1,6})?$"
      },
      "merchant_id": {
       "type": "string",
       "maxLength": 160,
       "minLength": 1
      },
      "trust_level": {
       "enum": [
        "unknown",
        "known",
        "verified"
       ],
       "type": "string"
      },
      "idempotency_key": {
       "type": "string",
       "maxLength": 128
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "network": {
       "type": "string"
      },
      "product": {
       "type": "string"
      },
      "activity": {
       "type": "object"
      },
      "identity": {
       "type": "object"
      },
      "assessment": {
       "type": "object"
      },
      "provenance": {
       "type": "object"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "network": "eip155:8453",
  "product": "nomos-merchant-trust",
  "assessment": {
   "flags": [],
   "risk_level": "low",
   "risk_score": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/nomos-merchant-trust-assessment-c30c3d6d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from base-agent-preflight.bytoken2023.workers.dev](https://www.zero.xyz/host/base-agent-preflight.bytoken2023.workers.dev/llms.txt)