# Blockscout Arbitrum Cross-Chain Message Lookup

> Blockscout Arbitrum Cross-Chain Message Lookup is a paid API for AI agents from api.blockscout.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).

Retrieves Arbitrum bridge messages for a given chain and direction (incoming or outgoing), returning message status, origination details, and completion transaction hashes.

## Facts

- Endpoint: GET https://api.blockscout.com/%7Bchain_id%7D/api/v2/arbitrum/messages/%7Bdirection%7D
- 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/blockscout-arbitrum-cross-chain-message-lookup-4cf6cdb6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_UOT1dk8wetmmtNl3UDESD

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 blockscout-arbitrum-cross-chain-message-lookup-4cf6cdb6
```

Example prompt: Can you pull the latest outgoing Arbitrum bridge messages on chain 42161 from Blockscout and show me their statuses and origination transaction hashes?

## When to prefer this

Use this endpoint when you need to specifically query Arbitrum cross-chain bridge messages in a given direction (incoming or outgoing) for a particular chain, especially when you need message status tracking, origination details, or completion transaction hashes for Arbitrum L2 bridge activity. Prefer this over generic transaction search when you specifically care about Arbitrum message passing semantics.

## Known failure modes

- Invalid chain_id returns 404 or empty results
- Invalid direction value causes a bad request error
- Non-existent message ID returns empty items array
- Rate limiting or payment failure returns 402 or 429
- Pagination with invalid items_count may return unexpected results

## How this service works

Explore crypto activities with Blockscout's multichain search. Find transactions, addresses, tokens, and dapps across top blockchain networks — your go-to explorer for cross-chain blockchain data

## Output

Returns a paginated list of Arbitrum bridge messages, each containing a numeric ID, status string, origination timestamp, origination address hash, origination transaction hash, origination block number, and completion transaction hash (if available), plus next_page_params for pagination.

## 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"
    },
    "pathParams": {
     "type": "object",
     "properties": {
      "chain_id": {
       "type": "string"
      },
      "direction": {
       "type": "string"
      }
     }
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "id": {
       "type": "integer"
      },
      "items_count": {
       "type": "integer"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "items": [
   {
    "id": 0,
    "status": "string",
    "origination_timestamp": "string",
    "origination_address_hash": "string",
    "completion_transaction_hash": "string",
    "origination_transaction_hash": "string",
    "origination_transaction_block_number": 0
   }
  ],
  "next_page_params": {}
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/blockscout-arbitrum-cross-chain-message-lookup-4cf6cdb6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.blockscout.com](https://www.zero.xyz/host/api.blockscout.com/llms.txt)