# BCS Cross-Chain Transaction Tracker via x402

> BCS Cross-Chain Transaction Tracker via x402 is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.29/call, status unknown (last checked 2026-09-14).

Looks up cross-chain bridge transaction status and provenance data by transaction hash and bridge protocol label, proxied through an x402 pay-per-call gateway.

## Facts

- Endpoint: GET https://base-agent-preflight.bytoken2023.workers.dev/v1/x402/bcs/cross-chain
- Price: $0.29/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bcs-cross-chain-transaction-tracker-via-x402-cbc43e24
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8VnRqR9d6puHSx17Kv9JY

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 bcs-cross-chain-transaction-tracker-via-x402-cbc43e24
```

Example prompt: Can you track my cross-chain bridge transaction — the source tx hash is 0xabc123def456789012345678901234567890abcd and I used the Wormhole bridge protocol?

## When to prefer this

Use this endpoint when you need to look up the status or provenance of a specific cross-chain bridge transaction by its source hash and know which bridge protocol was used (e.g. across, axelar, celer, wormhole). It is best suited for point-in-time transaction lookups rather than continuous monitoring. Prefer this over generic block explorers when you need structured, programmatic data from BlockchainSecurity Atlantis via a pay-per-call x402 interface.

## Known failure modes

- Invalid or malformed txhash (must match pattern ^[A-Za-z0-9:_-]{16,160}$) returns a validation error
- Unknown or unsupported bridge protocol label causes upstream lookup failure
- Transaction hash not found in the upstream BlockchainSecurity Atlantis database returns empty data
- Payment failure or insufficient USDC balance blocks the x402 gateway from proxying the request
- Network timeout from the upstream blockchainsecurity-atlantis service

## 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 product identifier (bcs-cross-chain-track), upstream service name (blockchainsecurity-atlantis), upstream response data with transaction details, and metadata including a request ID. Credit cost and remaining credit fields are also included in the upstream headers.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "txhash",
      "label"
     ],
     "properties": {
      "label": {
       "type": "string",
       "pattern": "^[A-Za-z0-9_-]{2,40}$",
       "description": "Bridge protocol label, such as across, axelar, celer, or wormhole."
      },
      "txhash": {
       "type": "string",
       "pattern": "^[A-Za-z0-9:_-]{16,160}$",
       "description": "Source transaction hash."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "product",
      "upstream_service",
      "upstream_response"
     ],
     "properties": {
      "product": {
       "type": "string"
      },
      "request": {
       "type": "object"
      },
      "provenance": {
       "type": "object"
      },
      "upstream_headers": {
       "type": "object"
      },
      "upstream_service": {
       "type": "string"
      },
      "upstream_response": {
       "type": "object"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "product": "bcs-cross-chain-track",
  "upstream_headers": {
   "request_id": "example-request-id",
   "credit_cost": null,
   "credit_remaining": null
  },
  "upstream_service": "blockchainsecurity-atlantis",
  "upstream_response": {
   "data": {},
   "meta": {
    "request_id": "example-request-id"
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/bcs-cross-chain-transaction-tracker-via-x402-cbc43e24/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)