How to Build Your Own MCP Server in 30 Minutes

Published August 2026 • 9 min read • Target keyword: build MCP server

While hundreds of MCP servers already exist, the real power comes from writing your own. In this tutorial you will build a fully functional MCP server that connects an AI agent to the CoinGecko API for real-time crypto prices — perfect for trading bots and portfolio trackers.

Project Setup

mkdir mcp-coingecko && cd mcp-coingecko
python -m venv venv && source venv/bin/activate
pip install mcp httpx

Core Server Code (server.py)

from mcp.server import Server
from mcp.types import Tool, TextContent
import httpx
import asyncio

server = Server("coingecko-mcp")

@server.list_tools()
async def list_tools():
    return [
        Tool(
            name="get_crypto_price",
            description="Get current price of any cryptocurrency",
            inputSchema={
                "type": "object",
                "properties": {
                    "coin_id": {"type": "string", "description": "CoinGecko coin ID (bitcoin, ethereum, etc.)"}
                },
                "required": ["coin_id"]
            }
        )
    ]

@server.call_tool()
async def call_tool(name, arguments):
    if name == "get_crypto_price":
        coin = arguments["coin_id"]
        async with httpx.AsyncClient() as client:
            r = await client.get(f"https://api.coingecko.com/api/v3/simple/price?ids={coin}&vs_currencies=usd")
            data = r.json()
            price = data.get(coin, {}).get("usd", "N/A")
            return [TextContent(type="text", text=f"Current {coin} price: ${price}")]
    return [TextContent(type="text", text="Unknown tool")]

if __name__ == "__main__":
    asyncio.run(server.run())

Testing Locally

Run the server with python server.py. Then in Claude Code or Codex add it as a local MCP server pointing to the script. Test the tool by asking your agent for the current Bitcoin price.

Publishing to the Registry

1. Push your repo to GitHub.
2. Add a proper README with install instructions.
3. Submit a PR to the official mcp-servers repository or use the registry submission form at mcp.dev/registry.

FAQ