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layout default
title Chapter 2: Weather Server Patterns Across Languages
nav_order 2
parent MCP Quickstart Resources Tutorial

Chapter 2: Weather Server Patterns Across Languages

Welcome to Chapter 2: Weather Server Patterns Across Languages. In this part of MCP Quickstart Resources Tutorial: Cross-Language MCP Servers and Clients by Example, you will build an intuitive mental model first, then move into concrete implementation details and practical production tradeoffs.

This chapter compares weather server implementations to highlight shared protocol behavior.

Learning Goals

  • identify common MCP server primitives in each runtime
  • compare runtime-specific setup/build differences
  • reason about maintainability tradeoffs by language
  • preserve behavior parity when customizing server examples

Comparison Lens

  1. tool declaration and tools/list response shape
  2. stdio transport setup and lifecycle handling
  3. dependency/runtime management per ecosystem
  4. local test and run commands

Source References

Summary

You now have a cross-language pattern model for MCP weather-server implementations.

Next: Chapter 3: MCP Client Patterns and LLM Chat Loops

Depth Expansion Playbook

Source Code Walkthrough

weather-server-python/weather.py

The get_forecast function in weather-server-python/weather.py handles a key part of this chapter's functionality:

@mcp.tool()
async def get_forecast(latitude: float, longitude: float) -> str:
    """Get weather forecast for a location.

    Args:
        latitude: Latitude of the location
        longitude: Longitude of the location
    """
    # First get the forecast grid endpoint
    points_url = f"{NWS_API_BASE}/points/{latitude},{longitude}"
    points_data = await make_nws_request(points_url)

    if not points_data:
        return "Unable to fetch forecast data for this location."

    # Get the forecast URL from the points response
    forecast_url = points_data["properties"]["forecast"]
    forecast_data = await make_nws_request(forecast_url)

    if not forecast_data:
        return "Unable to fetch detailed forecast."

    # Format the periods into a readable forecast
    periods = forecast_data["properties"]["periods"]
    forecasts = []
    for period in periods[:5]:  # Only show next 5 periods
        forecast = f"""
{period["name"]}:
Temperature: {period["temperature"]}°{period["temperatureUnit"]}
Wind: {period["windSpeed"]} {period["windDirection"]}
Forecast: {period["detailedForecast"]}

This function is important because it defines how MCP Quickstart Resources Tutorial: Cross-Language MCP Servers and Clients by Example implements the patterns covered in this chapter.

weather-server-python/weather.py

The main function in weather-server-python/weather.py handles a key part of this chapter's functionality:

def main():
    # Initialize and run the server
    mcp.run(transport="stdio")


if __name__ == "__main__":
    main()

This function is important because it defines how MCP Quickstart Resources Tutorial: Cross-Language MCP Servers and Clients by Example implements the patterns covered in this chapter.

mcp-client-go/main.go

The NewMCPClient function in mcp-client-go/main.go handles a key part of this chapter's functionality:

}

func NewMCPClient() (*MCPClient, error) {
	// Load .env file
	if err := godotenv.Load(); err != nil {
		return nil, fmt.Errorf("failed to load .env file: %w", err)
	}

	apiKey := os.Getenv("ANTHROPIC_API_KEY")
	if apiKey == "" {
		return nil, fmt.Errorf("ANTHROPIC_API_KEY environment variable not set")
	}

	client := anthropic.NewClient(option.WithAPIKey(apiKey))

	return &MCPClient{
		anthropic: &client,
	}, nil
}

func (c *MCPClient) ConnectToServer(ctx context.Context, serverArgs []string) error {
	if len(serverArgs) == 0 {
		return fmt.Errorf("no server command provided")
	}

	// Create command to spawn server process
	cmd := exec.CommandContext(ctx, serverArgs[0], serverArgs[1:]...)

	// Create MCP client
	client := mcp.NewClient(
		&mcp.Implementation{
			Name:    "mcp-client-go",

This function is important because it defines how MCP Quickstart Resources Tutorial: Cross-Language MCP Servers and Clients by Example implements the patterns covered in this chapter.

mcp-client-go/main.go

The ConnectToServer function in mcp-client-go/main.go handles a key part of this chapter's functionality:

}

func (c *MCPClient) ConnectToServer(ctx context.Context, serverArgs []string) error {
	if len(serverArgs) == 0 {
		return fmt.Errorf("no server command provided")
	}

	// Create command to spawn server process
	cmd := exec.CommandContext(ctx, serverArgs[0], serverArgs[1:]...)

	// Create MCP client
	client := mcp.NewClient(
		&mcp.Implementation{
			Name:    "mcp-client-go",
			Version: "0.1.0",
		},
		nil,
	)

	// Connect using CommandTransport
	transport := &mcp.CommandTransport{
		Command: cmd,
	}

	session, err := client.Connect(ctx, transport, nil)
	if err != nil {
		return fmt.Errorf("failed to connect to server: %w", err)
	}

	c.session = session

	// List available tools

This function is important because it defines how MCP Quickstart Resources Tutorial: Cross-Language MCP Servers and Clients by Example implements the patterns covered in this chapter.

How These Components Connect

flowchart TD
    A[get_forecast]
    B[main]
    C[NewMCPClient]
    D[ConnectToServer]
    E[mcpToolToAnthropicTool]
    A --> B
    B --> C
    C --> D
    D --> E
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