Monad MCP Tutorial

This project demonstrates how to create a MCP server that interacts with the Monad testnet. The MCP server provides a tool for checking MON token balances on the Monad testnet.

What is MCP?

The Model Context Protocol (MCP) is a standard that allows AI models to interact with external tools and services.

In this tutorial, we're creating an MCP server that allows MCP Client (Claude Desktop) to query Monad testnet to check MON balance of an account.

Prerequisites

• Node.js (v16 or later)
• npm or yarn
• Claude Desktop

Getting Started

1. Clone this repository

git clone https://github.com/monad-developers/monad-mcp-tutorial.git

2. Install dependencies:

npm install

Building the MCP server

Monad Testnet related configuration is already added to index.ts in the src folder.

Define the server instance

// Create a new MCP server instance
const server = new McpServer({
  name: "monad-testnet",
  version: "0.0.1",
  // Array of supported tool names that clients can call
  capabilities: ["get-mon-balance"]
});

Defining the MON balance tool

Below is the scaffold of the get-mon-balance tool:

server.tool(
    // Tool ID 
    "get-mon-balance",
    // Description of what the tool does
    "Get MON balance for an address on Monad testnet",
    // Input schema
    {
        address: z.string().describe("Monad testnet address to check balance for"),
    },
    // Tool implementation
    async ({ address }) => {
        // code to check MON balance
    }
);

Let's add the MON balance check implementation to the tool:

server.tool(
    // Tool ID 
    "get-mon-balance",
    // Description of what the tool does
    "Get MON balance for an address on Monad testnet",
    // Input schema
    {
        address: z.string().describe("Monad testnet address to check balance for"),
    },
    // Tool implementation
    async ({ address }) => {
        try {
            // Check MON balance for the input address
            const balance = await publicClient.getBalance({
                address: address as `0x${string}`,
            });

            // Return a human friendly message indicating the balance.
            return {
                content: [
                    {
                        type: "text",
                        text: `Balance for ${address}: ${formatUnits(balance, 18)} MON`,
                    },
                ],
            };
        } catch (error) {
            // If the balance check process fails, return a graceful message back to the MCP client indicating a failure.
            return {
                content: [
                    {
                        type: "text",
                        text: `Failed to retrieve balance for address: ${address}. Error: ${
                        error instanceof Error ? error.message : String(error)
                        }`,
                    },
                ],
            };
        }
    }
);

Initialize the transport and server from the main function

async function main() {
    // Create a transport layer using standard input/output
    const transport = new StdioServerTransport();
    
    // Connect the server to the transport
    await server.connect(transport);
    
    console.error("Monad testnet MCP Server running on stdio");
}

Build the project

npm run build

The server is now ready to use!

Adding the MCP server to Claude Desktop

1. Open "Claude Desktop"

2. Open Settings

Claude > Settings > Developer

3. Open claude_desktop_config.json

4. Add details about the MCP server and save the file.

{
  "mcpServers": {
    ...
    "monad-mcp": {
      "command": "node",
      "args": [
        "/<path-to-project>/build/index.js"
      ]
    }
  }
}

5. Restart "Claude Desktop"

Using the MCP server

Here's the final result

Further Resources

• Model Context Protocol Documentation
• Monad Documentation
• Viem Documentation