For official documentation, see the Anthropic Claude Code docs. MCP specifications are available at modelcontextprotocol.io.
Claude Code is powerful on its own, but connecting a Claude Code MCP server takes automation to a completely different level. Gmail operations, browser control, desktop manipulation — virtually any external tool can be called directly from Claude Code through MCP.
In this article, I explain the MCP concept, walk through the configuration, and introduce every custom Claude Code MCP server I run in production.
What Is a Claude Code MCP Server?
MCP stands for Model Context Protocol — a standardized way to give AI access to tools. The difference from traditional APIs is clear: APIs require humans to write code and make calls, whereas MCP lets AI decide when and how to invoke tools on its own.
In practice, once you connect a Claude Code MCP server, the AI automatically calls Gmail when it determines an email needs to be sent. No human intervention is required. Furthermore, since MCP is a standardized protocol, servers you build work with any MCP-compatible AI client.
📊 MCP Connection Architecture
.mcp.json — Connection Configuration
MCP server connections are managed through a .mcp.json file at the project root. The configuration is straightforward — just specify the startup command and path:
{
"mcpServers": {
"k-chrome": {
"command": "python",
"args": ["mcp-job-wrapper", ".claude/mcp-servers/k-chrome/server.py"]
},
"k-gmail": {
"command": "python",
"args": ["mcp-job-wrapper", ".claude/mcp-servers/k-gmail/server.py"]
},
"Windows-MCP": {
"command": "npx",
"args": ["-y", "windows-mcp"]
}
}
}When Claude Code starts, all configured MCP servers launch automatically. Therefore, there is no need to start servers individually.
Custom MCP Servers I Run
k-chrome — Browser Automation
A custom Claude Code MCP server built on Chrome DevTools Protocol for browser automation. It supports page navigation, clicking, form input, screenshot capture, and JavaScript execution. Most importantly, it uses your existing Chrome profile, so all login sessions (Google, Amazon, etc.) are preserved. As a result, there is no need to re-authenticate for each automation task.
k-gmail — Email Operations
A custom MCP server built on the Gmail API. It handles email search, retrieval, draft creation, sending, and attachment support. For example, saying “Send the invoice by email” triggers automatic PDF attachment and delivery. Additionally, it supports thread-level retrieval for monitoring reply chains.
Windows-MCP — Desktop Control
An existing npm package that enables full Windows desktop control. It supports app launching, screenshot-based coordinate detection, keyboard input, and PowerShell execution. This Claude Code MCP server is essential for operating non-browser applications like the LINE PC app.
monthly-invoice — Invoice Processing
A specialized MCP server for monthly invoice automation. It handles Excel template editing, PDF conversion, invoice number generation, and overtime calculation.
Official Remote MCP Servers
Beyond custom servers, Anthropic offers official remote MCP servers that you can connect with one click:
- Canva — Design generation, editing, and export
- Google Calendar — Event creation, viewing, and management
- Kiwi.com — Global flight search and comparison
- Slack / Notion — Team collaboration integrations
These remote servers are available from Anthropic’s MCP marketplace. Combined with custom servers, they dramatically expand Claude Code’s automation capabilities.
Building Your Own Claude Code MCP Server
With Python’s mcp library, you can create a Claude Code MCP server in just a few dozen lines:
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("my-server")
@mcp.tool()
def hello(name: str) -> str:
"""Greet someone"""
return f"Hello, {name}!"
if __name__ == "__main__":
mcp.run()Functions decorated with @mcp.tool() become callable tools in Claude Code. The docstring serves as the tool description, and type hints automatically generate the parameter schema. Once built, simply add the server to .mcp.json and restart Claude Code.
Next Up
The next article covers Custom Skills. You will learn how to create one-command automations for Amazon purchases, restaurant reservations, LINE messaging, and more.
