Your First MCP Server

Time to get hands-on with your first MCP server! We've provided all the code for you here, which we'll teach in the next video, but take a look at the flow of the code:

An MCP server instance is defined with FastMCP()
A tool function (convert_currency()) is written to perform some action; in this case, retrieving currency information from the Frankfurter API.
This function is converted into an MCP tool using the @mcp.tool() decorator.

This exercise is part of the course

Introduction to Model Context Protocol (MCP)

View Course

Exercise instructions

Take a look at the code provided to see how a function is converted into a tool for an MCP server.
On line 43, test the MCP tool with an amount and your choice of currencies to convert to and from.

Note: You'll need to use the official currency codes, like GBP for the British pound sterling.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

# Create an MCP server instance
mcp = FastMCP("Currency Converter")

@mcp.tool()
def convert_currency(amount: float, from_currency: str, to_currency: str) -> str:
    """
    Convert an amount from one currency to another using current exchange rates.

    Args:
        amount: The amount to convert
        from_currency: Source currency code (e.g., 'USD', 'EUR', 'GBP')
        to_currency: Target currency code (e.g., 'USD', 'EUR', 'GBP')

    Returns:
        A string with the conversion result and exchange rate
    """
    # API endpoint for Frankfurter
    url = f"https://api.frankfurter.dev/v1/latest?base={from_currency}&symbols={to_currency}"

    try:
        # Make the API request
        response = requests.get(url)
        response.raise_for_status()

        # Parse the response
        data = response.json()

        # Get the exchange rate
        rate = data['rates'].get(to_currency)

        if rate is None:
            return f"Could not find exchange rate for {from_currency} to {to_currency}"

        # Calculate the converted amount
        converted_amount = amount * rate

        return f"{amount} {from_currency} = {converted_amount:.2f} {to_currency} (Rate: {rate})"

    except requests.exceptions.RequestException as e:
        return f"Error converting currency: {str(e)}"

print("Testing Currency Converter:")
result = convert_currency(amount=100, from_currency="USD", to_currency="EUR")
print(result)

Edit and Run Code