Firecrawl Simple MCP

🚀 FastMCP Quick Reference Manual

FastMCP is a powerful tool that simplifies the implementation of the Model Context Protocol (MCP). This guide will help you quickly get started with FastMCP and understand its core concepts, advanced features, and configuration options.

🚀 Quick Start

📦 Installation

Install FastMCP via npm:

npm install fastmcp

Or use yarn:

yarn add fastmcp

🛠️ Create an MCP Server

Create a new TypeScript file (e.g., index.ts) and add the following code:

import { createMCPServer } from 'fastmcp';

async function main() {
    const server = await createMCPServer();

    // Define a simple capability: return the contents of the current directory
    server.addCapability('ls', async () => {
        return {
            type: 'text',
            text: process.cwd()
        };
    });

    await server.start();
}

main().catch(console.error);

▶️ Run Your Service

Run your service using the following command:

node index.ts

✨ Features

🌟 MCP Server

MCPServer is the core of FastMCP, used to manage capabilities and handle client requests.

🛠️ Create an MCP Server

import { createMCPServer } from 'fastmcp';

async function main() {
    const server = await createMCPServer();
    // ...
}

📋 Define Capabilities

Use the addCapability method to define server capabilities:

server.addCapability('my_capability', async () => {
    return { type: 'text', text: 'Hello, World!' };
});

▶️ Start the Server

Call the start method to start the MCP server:

await server.start();

💬 Session Management

Each connected client creates an MCPSession instance.

📖 Get the Current Session

You can get the current session as follows:

const session = await server.currentSession;

📨 Send a Message

Use the sendMessage method to send a message to the client:

await session.sendMessage({
    role: 'assistant',
    content: { type: 'text', text: 'Hello, World!' }
});

🎯 Sampling Request

MCP provides the requestSampling method for sampling requests.

📝 Example Code

await session.requestSampling({
    messages: [
        {
            role: 'user',
            content: { type: 'text', text: 'What files are in the current directory?' }
        }
    ],
    systemPrompt: 'You are a helpful file system assistant.',
    includeContext: 'thisServer'
});

💻 Advanced Usage

📋 Define Capabilities

You can add custom capabilities to the server using the addCapability method.

📝 Example Code

server.addCapability('searchFiles', async (query) => {
    // Implement file search logic here
    return { type: 'text', text: `Searching for files matching ${query}` };
});

🎧 Event Listening

MCP provides rich event listening capabilities. You can listen for various events on the page.

📻 Listen for Server Events

server.on('connection', () => {
    console.log('New client connected');
});

server.on('disconnection', () => {
    console.log('Client disconnected');
});

📻 Listen for Session Events

session.on('message', (message) => {
    console.log('Received message:', message);
});

session.on('error', (error) => {
    console.error('Session error:', error);
});

⚙️ Configuration Options

🚀 Startup Configuration

You can customize the server's startup behavior by passing a configuration object.

📝 Example Code

await createMCPServer({
    port: 3000,
    host: 'localhost',
    capabilities: {
        my_capability: () => ({
            type: 'text',
            text: 'Hello, World!'
        })
    }
});

💬 Session Configuration

You can adjust certain client behaviors through session configuration.

📝 Example Code

session.setClientCapabilities({
    experimentalFeatures: true,
    loggingLevel: 'debug'
});

🛠️ Tools and Resources

📄 MCP CLI

Use the fastmcp dev command to quickly start a development server:

npx fastmcp dev server.js
npx fastmcp dev server.ts

📊 MCP Monitor

Use the official MCP Monitor to check your server via the Web UI:

npx fastmcp inspect server.ts

❓ Frequently Asked Questions

❓ How to Use with Claude Desktop?

Follow the guide here and add the following configuration:

{
  "mcpServers": {
    "my-mcp-server": {
      "command": "node",
      "args": ["index.js"]
    }
  }
}

❓ How to Handle Custom Protocols?

FastMCP currently supports the standard MCP protocol and does not support custom protocols. Please stay tuned for future version updates.

📚 Tutorials and Examples

📂 Simple File Manager

Create a basic file management capability:

server.addCapability('listFiles', async () => {
    const files = await fs.promises.readdir('.');
    return {
        type: 'text',
        text: files.join('\n')
    };
});

📄 Documentation

📖 MCP Server API

• createMCPServer([config]): Promise<MCPServer>
• MCPServer.start(): Promise<void>
• MCPServer.addCapability(name, callback): void
• MCPServer.on(event, listener): void

📖 MCP Session API

• MCPSession.sendMessage(message): Promise<void>
• MCPSession.requestSampling(options): Promise<any>
• MCPSession.setClientCapabilities(capabilities): void