Building MCP Tools and Running Them in Cursor Editor

{
  "name": "mcp-tools",
  "type": "module",
  "dependencies": {
    "@modelcontextprotocol/sdk": "^1.4.0",
    "zod": "^3.24.1"
  },
  "scripts": {
    "build": "pnpm build:all",
    "build:hello": "mkdir -p bin && bun build src/hello.ts --compile --minify --sourcemap --outfile bin/mcp-hello",
    "build:weather": "mkdir -p bin && bun build src/weather.ts --compile --minify --sourcemap --outfile bin/mcp-weather"
  }
}

pnpm install

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";

// Create an MCP server instance
const server = new McpServer({
    name: "weather-tool",
    version: "1.0.0",
});

// Register a weather alerts tool
server.tool(
    "get_alerts",
    "Get weather alerts for a state",
    {
        state: z.string().min(2).max(2).describe("Two-letter state code (e.g. CA, NY)"),
    },
    async ({ state }) => {
        // In a real implementation, this would call a weather API
        // For this example, we'll just return mock data
        const mockAlerts = {
            "CA": ["Wildfire warning in Northern California", "Heat advisory in Southern California"],
            "NY": ["Flood warning in Western New York", "Thunderstorm watch in NYC metro area"],
            "FL": ["Hurricane watch along the coast", "Flood warning in South Florida"],
        };

        const alerts = (mockAlerts as Record<string, string[]>)[state] || ["No current alerts for this state"];

        return {
            content: [
                {
                    type: "text",
                    text: `Weather Alerts for ${state}:\n${alerts.map(alert => `- ${alert}`).join('\n')}`,
                },
            ],
        };
    }
);

// Start the server using stdio transport
async function main() {
    const transport = new StdioServerTransport();
    await server.connect(transport);
    console.error("Weather MCP Tool running on stdio");
}

main().catch((error) => {
    console.error("Fatal error:", error);
    process.exit(1);
}); 

pnpm build:weather

./bin/mcp-weather

Weather MCP Tool running on stdio

pnpm watch:weather

pnpm build         # build all tools
pnpm build:weather # build weather tool

# Run the binary
./bin/mcp-weather

# Watch mode (auto-rebuild)
pnpm watch:weather