Building an MCP Server to Connect LLMs to Rootstock

The Model Context Protocol (MCP) is an open standard that allows AI models (like Claude or Cursor) to securely interact with external data and tools. By building a Rootstock MCP server, you enable AI agents to read balances, query smart contracts, and track transactions directly using natural language.

Prerequisites

• Node.js (v18+) and npm installed.
• Rootstock RPC URL: Access to a node (e.g., via Rootstock's public nodes).
• MCP Inspector: For testing your server locally.

Getting Started

1. Initialize the Server

Create a new TypeScript project and install the official MCP SDK.

mkdir rootstock-mcp && cd rootstock-mcp
npm init -y
npm install @modelcontextprotocol/sdk viem

2. Implement the Blockchain Tool

Define a "Tool" that the AI can call. In this example, we create a tool that allows the AI to fetch the rBTC balance of any address.

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { createPublicClient, http, formatEther } from "viem";

const server = new McpServer({ name: "Rootstock", version: "1.0.0" });
const publicClient = createPublicClient({ transport: http('[https://public-node.testnet.rsk.co](https://public-node.testnet.rsk.co)') });

// Register the "get_balance" tool
server.tool("get_balance", { address: z.string() }, async ({ address }) => {
  const balance = await publicClient.getBalance({ address: address as `0x${string}` });
  return {
    content: [{ type: "text", text: `Balance: ${formatEther(balance)} rBTC` }]
  };
});

// Start the server using stdio transport
const transport = new StdioServerTransport();
await server.connect(transport);

3. Testing with MCP Inspector

Run the inspector to simulate an AI client calling your Rootstock tools.

npx @modelcontextprotocol/inspector node build/index.js

Troubleshooting

• Connection Timeouts: Ensure your RPC provider isn't rate-limiting the MCP server during intensive AI sessions.

• Context Window Overload: AI models have limits. When returning contract ABIs or large transaction histories, truncate the data to keep the most relevant context.

Related Use Cases or Resources

• Official Rootstock MCP Server Repository

• Autonomous BTCFi Agents

• Querying On-Chain Data