# SignGate Agent Buyer Identity Preflight – Sumsub Payment Method Crypto Evidence

> SignGate Agent Buyer Identity Preflight – Sumsub Payment Method Crypto Evidence is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.03/call, status unknown (last checked 2026-09-15).

Verifies KYC/AML risk level of a crypto wallet address against a Sumsub applicant identity before an AI agent executes an x402 micropayment purchase.

## Facts

- Endpoint: GET https://base-agent-preflight.bytoken2023.workers.dev/v1/x402/sumsub/payment-method-crypto-evidence
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signgate-agent-buyer-identity-preflight-sumsub-payment-method-crypto-87fcf0d1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VSHkJ-jV_Z5dyRoMCHSIj

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 signgate-agent-buyer-identity-preflight-sumsub-payment-method-crypto-87fcf0d1
```

Example prompt: Before my AI agent buys that x402 dataset, run a preflight identity check on Sumsub applicant 'user-abc123' using wallet address 0xAbCd1234567890AbCd1234567890AbCd12345678 to confirm the risk level is acceptable.

## When to prefer this

Use this endpoint when an AI agent operating under x402 payment governance needs to verify that the purchasing wallet and its associated Sumsub KYC identity are compliant before executing a crypto micropayment. Prefer this over generic wallet screening tools when the workflow is specifically x402-protocol-based and Sumsub is the identity provider, especially for Base network (eip155:8453) transactions where buyer role eligibility and AML risk must be confirmed programmatically before the agent spends funds.

## Known failure modes

- Invalid wallet address format (not a valid 0x hex address) returns a validation error
- Unknown or non-existent Sumsub applicant_id returns a not-found or fixture error
- High risk score or flagged wallet results in a non-low risk_level in the assessment, blocking purchase
- Network or Cloudflare Worker timeout returns a 5xx error
- Missing required query parameters returns a 400 bad request

## 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 Base network identifier (eip155:8453), product name (sumsub-payment-method-crypto-evidence), and an assessment object containing a risk_score (numeric), risk_level (e.g. 'low'), and flags array listing any AML/KYC concerns found for the wallet-applicant pair.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "applicant_id",
      "wallet"
     ],
     "properties": {
      "wallet": {
       "type": "string",
       "pattern": "^0x[a-fA-F0-9]{40}$",
       "description": "Crypto wallet/payment method address."
      },
      "applicant_id": {
       "type": "string",
       "pattern": "^[A-Za-z0-9._:-]{1,128}$",
       "description": "Sumsub applicant id or sandbox fixture reference."
      }
     }
    }
   },
   "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": "sumsub-payment-method-crypto-evidence",
  "assessment": {
   "flags": [],
   "risk_level": "low",
   "risk_score": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signgate-agent-buyer-identity-preflight-sumsub-payment-method-crypto-87fcf0d1/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)