import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";
import os from "os";
// Create an MCP server
const server = new McpServer({
name: "Node.js MCP Server",
version: "1.0.0",
});
// Export handlers for testing
export const calculateHandler = async ({ operation, a, b }: { operation: "add" | "subtract" | "multiply" | "divide", a: number, b: number }) => {
switch (operation) {
case "add":
return { content: [{ type: "text" as const, text: String(a + b) }] };
case "subtract":
return { content: [{ type: "text" as const, text: String(a - b) }] };
case "multiply":
return { content: [{ type: "text" as const, text: String(a * b) }] };
case "divide":
if (b === 0) {
return { content: [{ type: "text" as const, text: "Error: Division by zero" }], isError: true };
}
return { content: [{ type: "text" as const, text: String(a / b) }] };
default:
return { content: [{ type: "text" as const, text: "Unknown operation" }], isError: true };
}
};
export const systemInfoHandler = async () => {
const info = {
platform: os.platform(),
release: os.release(),
arch: os.arch(),
cpus: os.cpus().length,
totalMem: `${Math.round(os.totalmem() / 1024 / 1024)} MB`,
freeMem: `${Math.round(os.freemem() / 1024 / 1024)} MB`,
};
return {
content: [{ type: "text" as const, text: JSON.stringify(info, null, 2) }],
};
};
// Add a calculator tool
server.tool(
"calculate",
{
operation: z.enum(["add", "subtract", "multiply", "divide"]).describe("The operation to perform"),
a: z.number().describe("The first number"),
b: z.number().describe("The second number"),
},
calculateHandler
);
// Add a system info tool
server.tool(
"get_system_info",
{},
systemInfoHandler
);
// Add a simple resource
server.resource(
"system",
"system://info",
async (uri) => {
const info = `System Info: ${os.platform()} ${os.release()} (${os.arch()})`;
return {
contents: [{
uri: uri.href,
text: info,
}],
};
}
);
async function main() {
const transport = new StdioServerTransport();
await server.connect(transport);
console.error("MCP Server running on stdio");
}
// Only run main if this file is the entry point
if (import.meta.url === `file://${process.argv[1]}`) {
main().catch((error) => {
console.error("Fatal error in main():", error);
process.exit(1);
});
}
