# SignGate Sumsub KYT Evidence Lookup

> SignGate Sumsub KYT Evidence Lookup 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 2026-09-14).

Retrieves Sumsub Know-Your-Transaction (KYT) evidence and risk assessment for a given transaction ID before an AI agent proceeds with an x402 micropayment purchase.

## Facts

- Endpoint: GET https://base-agent-preflight.bytoken2023.workers.dev/v1/x402/sumsub/kyt-evidence
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signgate-sumsub-kyt-evidence-lookup-5b58cc22
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jo-JFsU1qZPWNWDQB0UKA

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-sumsub-kyt-evidence-lookup-5b58cc22
```

Example prompt: Before paying for that x402 API, run a KYT preflight check on Sumsub transaction ID 'txn-abc123xyz' on the Base network to make sure the risk level is low and there are no compliance flags.

## When to prefer this

Use this endpoint when an AI agent needs to perform a compliance preflight check on a specific Sumsub transaction ID before executing an x402 micropayment on the Base network. Prefer it over generic blockchain analytics when you specifically have a Sumsub transaction reference and need KYT evidence with structured risk scoring and flags. It is especially suited for agentic purchase governance workflows where policy requires low risk_level confirmation before proceeding.

## Known failure modes

- Missing or invalid transaction_id returns a 400 or validation error
- Unknown transaction_id that Sumsub has no record of may return empty or null assessment
- Malformed asset or chain identifiers (not matching pattern ^[A-Za-z0-9._:-]{2,32}$) cause schema validation failure
- Service unavailable on the Cloudflare Workers edge returns 5xx
- Payment not made (x402 gate) returns 402 Payment Required before any data is served

## 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 containing the network (e.g. eip155:8453), product identifier, and an assessment object with risk_level (e.g. 'low'), risk_score (numeric), flags array, plus optional activity, identity, and provenance sub-objects for the queried transaction.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "transaction_id"
     ],
     "properties": {
      "asset": {
       "type": "string",
       "pattern": "^[A-Za-z0-9._:-]{2,32}$"
      },
      "chain": {
       "type": "string",
       "pattern": "^[A-Za-z0-9._:-]{2,64}$"
      },
      "transaction_id": {
       "type": "string",
       "pattern": "^[A-Za-z0-9._:-]{1,128}$",
       "description": "Sumsub transaction id, SignGate transaction reference, or sandbox fixture id."
      }
     }
    }
   },
   "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-kyt-evidence",
  "assessment": {
   "flags": [],
   "risk_level": "low",
   "risk_score": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signgate-sumsub-kyt-evidence-lookup-5b58cc22/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)