Fewsats MCP Server

Instructions

Creates a payment header for the X402 protocol.

The chain is base-sepolia or base
The x402 payload must be a dict with this structure:
{
    "accepts": [
        {
            "asset": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
            "description": "Payment for GET https://proxy402.com/7Yhuf2O3zs",
            "extra": {
                "name": "USDC",
                "version": "2"
            },
            "maxAmountRequired": "10",
            "maxTimeoutSeconds": 300,
            "mimeType": "",
            "network": "base-sepolia",
            "payTo": "0xbA5Ae80f48E0C74878c1a362D69c27c2135Aa594",
            "resource": "https://proxy402.com/7Yhuf2O3zs",
            "scheme": "exact"
        }
    ],
    "error": "X-PAYMENT header is required",
    "x402Version": 1
}

Returns a dict with the payment_header field that must be set in X-PAYMENT header in a x402 http request.

Implementation Reference

• src/fewsats_mcp/server.py:66-97 (handler)

  The handler function for the 'create_x402_payment_header' tool. It is registered via @mcp.tool() decorator and implements the logic by calling Fewsats().pay_x402_offer(x402_payload, chain) wrapped in handle_response.

  @mcp.tool()
  async def create_x402_payment_header(chain: str, x402_payload: dict) -> dict:
      """
      Creates a payment header for the X402 protocol.
  
      The chain is base-sepolia or base
      The x402 payload must be a dict with this structure:
      {
          "accepts": [
              {
                  "asset": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
                  "description": "Payment for GET https://proxy402.com/7Yhuf2O3zs",
                  "extra": {
                      "name": "USDC",
                      "version": "2"
                  },
                  "maxAmountRequired": "10",
                  "maxTimeoutSeconds": 300,
                  "mimeType": "",
                  "network": "base-sepolia",
                  "payTo": "0xbA5Ae80f48E0C74878c1a362D69c27c2135Aa594",
                  "resource": "https://proxy402.com/7Yhuf2O3zs",
                  "scheme": "exact"
              }
          ],
          "error": "X-PAYMENT header is required",
          "x402Version": 1
      }
  
      Returns a dict with the payment_header field that must be set in X-PAYMENT header in a x402 http request.
      """
      return handle_response(Fewsats().pay_x402_offer(x402_payload, chain))

• src/fewsats_mcp/server.py:68-96 (schema)

  The docstring provides the input schema example for 'x402_payload' dictionary and describes the parameters 'chain' and the expected output format.

  """
  Creates a payment header for the X402 protocol.
  
  The chain is base-sepolia or base
  The x402 payload must be a dict with this structure:
  {
      "accepts": [
          {
              "asset": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
              "description": "Payment for GET https://proxy402.com/7Yhuf2O3zs",
              "extra": {
                  "name": "USDC",
                  "version": "2"
              },
              "maxAmountRequired": "10",
              "maxTimeoutSeconds": 300,
              "mimeType": "",
              "network": "base-sepolia",
              "payTo": "0xbA5Ae80f48E0C74878c1a362D69c27c2135Aa594",
              "resource": "https://proxy402.com/7Yhuf2O3zs",
              "scheme": "exact"
          }
      ],
      "error": "X-PAYMENT header is required",
      "x402Version": 1
  }
  
  Returns a dict with the payment_header field that must be set in X-PAYMENT header in a x402 http request.
  """

• src/fewsats_mcp/server.py:66-66 (registration)

  The @mcp.tool() decorator registers the create_x402_payment_header function as an MCP tool.

  @mcp.tool()