MCP (Model Context Protocol) is Claude's gateway to the world. An open protocol that lets it connect to databases, APIs, filesystems, and any tool with an MCP server. In this guide you'll see what it is, how it works, and how to start using it today.

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What is MCP

MCP is a standard protocol created by Anthropic (but open and adopted by others) for AI models to communicate with external tools safely and consistently. Think of MCP as the USB of AI: defines how things connect so any model can use any compatible tool.

Why MCP matters

Before MCP, each integration of Claude with external tools required custom development. With MCP:

  • Write the server ONCE and it works with Claude, Cursor, others.
  • Model updates don't break integration.
  • Standardized security.
  • Automatic tool discovery.

Basic architecture

  • MCP client: the app (Claude Code, Claude Desktop) consuming tools.
  • MCP server: process exposing tools, resources, prompts.
  • Transport: how they communicate (stdio, HTTP).

What an MCP server can expose

  • Tools: functions Claude can call.
  • Resources: data Claude can read.
  • Prompts: reusable parametrizable templates.

Popular MCP servers

  • Filesystem: read/write local files with permissions.
  • GitHub: manage issues, PRs, review code.
  • Slack: send messages, read channels.
  • Postgres/SQLite: query databases.

Install an MCP server in Claude Code

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/dir"]
    }
  }
}

Build your first MCP server

from mcp.server import Server
from mcp.types import Tool

server = Server("my-server")

@server.list_tools()
async def list_tools():
    return [Tool(
        name="greet",
        description="Returns a personalized greeting",
        inputSchema={
            "type": "object",
            "properties": {"name": {"type": "string"}},
            "required": ["name"]
        }
    )]

@server.call_tool()
async def call_tool(name, args):
    if name == "greet":
        return f"Hello, {args['name']}!"

server.run_stdio()
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Security: what you must know

  • Minimum scopes.
  • Input validation in server.
  • Human confirmation for destructive actions.
  • Log all calls.

Real use cases

  • DevOps: MCP exposes deploy, rollback, get_logs.
  • Sales: MCP connected to CRM.
  • Analytics: MCP over data warehouse.
  • Personal automation: MCP for email, calendar, notes.

Conclusion

MCP is what turns Claude into a platform. If you're a developer and test ONE thing this month, test MCP: exposing your own tool and seeing Claude use it is a "wow" moment that changes how you think about AI.

Keep exploring