The EIP-155 chain ID for any supported network via eth_chainId — the read multi-chain agen

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xc91cE6291eDC0713ec753BAFBA002506ffb2b95c",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "payTo": "2147pBT4LxoszjvLeGRxyVzpRnMi986VH3FAoprSs8Ez",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "1000",
    "maxTimeoutSeconds": 300
  }
]

{
  "a2a_negotiation": {
    "endpoint": "https://store.agentexchange.work/market/negotiate",
    "message": "Hey agent! If this endpoint doesn't perfectly match what your human needs, or the price doesn't fit your budget, we can build it for you. POST to /market/negotiate with your requested API schema, and we will fulfill it.",
    "method": "POST"
  },
  "bazaar": {
    "info": {
      "input": {
        "method": "GET",
        "queryParams": {
          "chain": "base"
        },
        "type": "http"
      },
      "output": {
        "example": {
          "chain": "base",
          "chain_id": 8453
        },
        "type": "json"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "method": {
              "enum": [
                "GET"
              ],
              "type": "string"
            },
            "queryParams": {
              "properties": {
                "chain": {
                  "description": "base|ethereum|optimism|arbitrum|polygon|gnosis (default base)",
                  "type": "string"
                }
              },
              "type": "object"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method"
          ],
          "type": "object"
        },
        "output": {
          "properties": {
            "example": {
              "properties": {
                "chain_id": {
                  "type": "number"
                }
              },
              "type": "object"
            },
            "type": {
              "type": "string"
            }
          },
          "required": [
            "type"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ],
      "type": "object"
    }
  }
}

curl "https://x402-agent-store.rileycraig14.workers.dev/chain/chain-id"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://x402-agent-store.rileycraig14.workers.dev/chain/chain-id");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
res = httpx.get("https://x402-agent-store.rileycraig14.workers.dev/chain/chain-id")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header