MCP Protocol: AI's USB Port — Plug-and-Play Tools

An Annoying Problem

Have you ever had this experience?

You want AI to “search for a document in Google Drive → summarize it → send it to Slack.”

Sounds simple in theory. But in practice:

• Google Drive’s API → one authentication method, one format
• Slack’s API → another authentication method, another format
• Notion’s API → yet another authentication method, yet another format

Every tool speaks its own “dialect.” You (or your AI) have to learn each one.

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What Is MCP? One Analogy Is All You Need

MCP = The USB standard for AI tools.

Remember the world before USB?

• Printers used LPT ports
• Mice used PS/2 ports
• Cameras had their own proprietary cables
• Phones had Micro USB, Mini USB, Lightning…

USB-C unified everything.

MCP does the same thing for AI. It defines a standard “communication protocol” that lets AI talk to all tools using the same language.

Before: AI → various different APIs → Google / Slack / Notion / …
Now:    AI → MCP protocol → Google / Slack / Notion / …

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The Full Name and Origin of MCP

MCP = Model Context Protocol

Proposed by Anthropic (the company behind Claude) in late 2024, it’s now adopted by major AI frameworks, including OpenClaw.

Why “Context Protocol”?

Because its core function is to feed external tool information (Context) into AI’s decision-making process in a standardized way.

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MCP Architecture: Three Roles

┌──────────┐     MCP Protocol    ┌──────────────┐     Actual Tools
│          │ ←─────────────────→ │              │ ←──────────→  Google Drive
│  MCP     │                     │  MCP Server  │               Slack
│  Client  │                     │  (Bridge)    │               Notion
│ (OpenClaw)│                     │              │               Any API
└──────────┘                     └──────────────┘

Role	What It Is	Example
MCP Client	The side that uses tools	OpenClaw Agent
MCP Server	The bridge that provides tool capabilities	google-drive-server, slack-server
Tool	The actual functionality	Search files, send messages, query databases

An Analogy

You (MCP Client) → Translator (MCP Server) → Foreign Client (Tool)

You only need to speak English to the translator (MCP protocol), and the translator will communicate in the other party’s language (various APIs).

Duck Editor says: To put it even more simply — MCP is like an internal phone system in an office. Whether you need to reach the finance department (Google Drive) or the marketing department (Slack), just dial the extension number. No need to walk to their office and learn their jargon.

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How Does MCP Work?

1. Discovery

The Client asks the Server: “What can you do?“

// Client → Server
{ "method": "tools/list" }

// Server → Client
{
  "tools": [
    {
      "name": "search_files",
      "description": "Search files in Google Drive",
      "inputSchema": {
        "type": "object",
        "properties": {
          "query": { "type": "string", "description": "Search keyword" }
        }
      }
    },
    {
      "name": "read_file",
      "description": "Read the contents of a specific file"
    }
  ]
}

2. Invocation

Once the Client knows what tools are available, it can use them:

// Client → Server
{
  "method": "tools/call",
  "params": {
    "name": "search_files",
    "arguments": { "query": "weekly meeting notes" }
  }
}

// Server → Client
{
  "content": [
    {
      "type": "text",
      "text": "Found 3 files:\n1. 2024-02 Weekly Meeting Notes\n2. ..."
    }
  ]
}

3. AI Decision-Making

After receiving the results, the Agent decides what to do next. This is the Agent’s ReAct workflow:

Observe: Found 3 weekly meeting notes
Think:   User wants the most recent one, pick the first
Act:     Call read_file to get its contents
Observe: Got the content
Think:   Summarize it
Act:     Call LLM to generate a summary

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Using MCP in OpenClaw

Installing an MCP Server

OpenClaw has a built-in MCP Client. You just need to start the corresponding MCP Server.

Using Google Drive as an example:

# Install Google Drive MCP Server
npm install -g @anthropic/mcp-server-google-drive

# Or use OpenClaw's built-in command
openclaw mcp install google-drive

Configuring the Connection

In OpenClaw’s config file config.yaml:

mcp_servers:
  google-drive:
    command: mcp-server-google-drive
    args:
      - --credentials=/path/to/credentials.json
    env:
      GOOGLE_API_KEY: ${GOOGLE_API_KEY}

  slack:
    command: mcp-server-slack
    env:
      SLACK_TOKEN: ${SLACK_TOKEN}

  notion:
    command: mcp-server-notion
    env:
      NOTION_TOKEN: ${NOTION_TOKEN}

After starting, your Agent can operate Google Drive, Slack, and Notion all at once.

Not sure how to set up a Google API Key? Check the Google API Key Setup Guide.

Confirming the Connection

# List all connected MCP Servers
openclaw mcp list

# Test a specific Server
openclaw mcp test google-drive

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What MCP Servers Are Available?

The ecosystem is growing fast. Here are the major Servers as of early 2026:

Productivity Tools

MCP Server	Features	Difficulty
Google Drive	Search, read/write files	⭐ Easy
Google Calendar	Schedule management	⭐ Easy
Gmail	Send/receive emails	⭐⭐ Medium
Notion	Knowledge base operations	⭐ Easy
Slack	Send/reply messages	⭐ Easy
Telegram	Chatbot	⭐⭐ Medium

Developer Tools

MCP Server	Features	Difficulty
GitHub	Repo / Issue / PR management	⭐⭐ Medium
Database (PostgreSQL)	Database queries	⭐⭐ Medium
Docker	Container management	⭐⭐⭐ Advanced
Kubernetes	Cluster management	⭐⭐⭐ Advanced

Data Sources

MCP Server	Features	Difficulty
Web Search	Web search	⭐ Easy
Web Scraper	Web scraping	⭐⭐ Medium
RSS	RSS feeds	⭐ Easy

You can find the full list on ClawHub.

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Why MCP Matters to You

1. No Need to Learn Every Tool’s API

Before: You had to read Google API docs + Slack API docs + Notion API docs…

Now: Install an MCP Server, and it works out of the box.

2. The Agent Automatically Selects Tools

You don’t need to specify “first search with Google, then save to Notion.” The Agent automatically determines which MCP Server’s tools to use based on your goal.

This is the power of an Agent.

3. Switch Tools Without Changing Your Workflow

Using Notion today but want to switch to Obsidian tomorrow? Just swap out one MCP Server — your Skills and Agent logic remain completely unchanged.

In other words: Before, switching from Notion to Obsidian was like moving house — packing, dismantling, reorganizing everything. With MCP, switching tools is like swapping a light switch cover plate — the wiring stays the same, you just replace one component.

4. Built-in Security

MCP has standard authentication and permission mechanisms:

# Restrict Agent to read-only, no writing
mcp_servers:
  google-drive:
    permissions:
      - search_files: allow
      - read_file: allow
      - write_file: deny   # No writing
      - delete_file: deny  # No deleting

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Advanced: Build Your Own MCP Server

If you need to connect internal systems or custom APIs, you can write your own MCP Server.

Minimal Example (Node.js)

import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";

const server = new Server({
  name: "my-custom-server",
  version: "1.0.0"
});

// Define a tool
server.setRequestHandler("tools/list", async () => ({
  tools: [{
    name: "get_weather",
    description: "Query weather for a specific city",
    inputSchema: {
      type: "object",
      properties: {
        city: { type: "string", description: "City name" }
      },
      required: ["city"]
    }
  }]
}));

// Implement tool logic
server.setRequestHandler("tools/call", async (request) => {
  if (request.params.name === "get_weather") {
    const city = request.params.arguments.city;
    // Call weather API...
    return {
      content: [{ type: "text", text: `${city}: Currently 25°C, Sunny` }]
    };
  }
});

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

The MCP SDK is currently available for Node.js and Python. If you can code, you can easily extend it.

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Frequently Asked Questions

What’s the difference between MCP and OpenAPI (Swagger)?

OpenAPI is a specification for defining REST APIs. MCP is a tool connection protocol specifically for AI. MCP is higher-level — it includes tool descriptions, authentication flows, and result formats that AI needs.

Are all MCP Servers free?

MCP Servers themselves are mostly open-source and free. However, the services they connect to (like Google API) may require an API Key and incur costs.

How many MCP Servers can I connect at once?

There’s no limit. OpenClaw can manage dozens of MCP Servers simultaneously, and the Agent will automatically select the right one based on the task.

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Next Steps

Now that you understand MCP, you can:

• 🔑 Apply for an API Key and connect your first service
• 🤖 Let the Agent automatically call MCP tools
• 🧩 Call MCP tools in your Skills
• ⚙️ Configure your model to drive MCP calls
• 💬 Connect Telegram as your AI entry point