from typing import Any import httpx from mcp.server.models import InitializationOptions import mcp.types as types from mcp.server import NotificationOptions, Server import mcp.server.stdio import asyncio NWS_API_BASE = "https://api.weather.gov" USER_AGENT = "weather-app/1.0" server = Server("weather") @server.list_tools() async def handle_list_tools() -> list[types.Tool]: """ List available tools. Each tool specifies its arguments using JSON Schema validation. """ return [ types.Tool( name="get-alerts", description="Get weather alerts for a state", inputSchema={ "type": "object", "properties": { "state": { "type": "string", "description": "Two-letter state code (e.g. CA, NY)", }, }, "required": ["state"], }, ), types.Tool( name="get-forecast", description="Get weather forecast for a location", inputSchema={ "type": "object", "properties": { "latitude": { "type": "number", "description": "Latitude of the location", }, "longitude": { "type": "number", "description": "Longitude of the location", }, }, "required": ["latitude", "longitude"], }, ), ] async def make_nws_request(client: httpx.AsyncClient, url: str) -> dict[str, Any] | None: """Make a request to the NWS API with proper error handling.""" headers = { "User-Agent": USER_AGENT, "Accept": "application/geo+json" } try: response = await client.get(url, headers=headers, timeout=30.0) response.raise_for_status() return response.json() except Exception: return None def format_alert(feature: dict) -> str: """Format an alert feature into a concise string.""" props = feature["properties"] return ( f"Event: {props.get('event', 'Unknown')}\n" f"Area: {props.get('areaDesc', 'Unknown')}\n" f"Severity: {props.get('severity', 'Unknown')}\n" f"Status: {props.get('status', 'Unknown')}\n" f"Headline: {props.get('headline', 'No headline')}\n" "---" ) @server.call_tool() async def handle_call_tool( name: str, arguments: dict | None ) -> list[types.TextContent | types.ImageContent | types.EmbeddedResource]: """ Handle tool execution requests. Tools can fetch weather data and notify clients of changes. """ if not arguments: raise ValueError("Missing arguments") if name == "get-alerts": state = arguments.get("state") if not state: raise ValueError("Missing state parameter") # Convert state to uppercase to ensure consistent format state = state.upper() if len(state) != 2: raise ValueError("State must be a two-letter code (e.g. CA, NY)") async with httpx.AsyncClient() as client: alerts_url = f"{NWS_API_BASE}/alerts?area={state}" alerts_data = await make_nws_request(client, alerts_url) if not alerts_data: return [types.TextContent(type="text", text="Failed to retrieve alerts data")] features = alerts_data.get("features", []) if not features: return [types.TextContent(type="text", text=f"No active alerts for {state}")] # Format each alert into a concise string formatted_alerts = [format_alert(feature) for feature in features] alerts_text = f"Active alerts for {state}:\n\n" + "\n".join(formatted_alerts) return [ types.TextContent( type="text", text=alerts_text ) ] elif name == "get-forecast": try: latitude = float(arguments.get("latitude")) longitude = float(arguments.get("longitude")) except (TypeError, ValueError): return [types.TextContent( type="text", text="Invalid coordinates. Please provide valid numbers for latitude and longitude." )] # Basic coordinate validation if not (-90 <= latitude <= 90) or not (-180 <= longitude <= 180): return [types.TextContent( type="text", text="Invalid coordinates. Latitude must be between -90 and 90, longitude between -180 and 180." )] async with httpx.AsyncClient() as client: # First get the grid point lat_str = f"{latitude}" lon_str = f"{longitude}" points_url = f"{NWS_API_BASE}/points/{lat_str},{lon_str}" points_data = await make_nws_request(client, points_url) if not points_data: return [types.TextContent(type="text", text=f"Failed to retrieve grid point data for coordinates: {latitude}, {longitude}. This location may not be supported by the NWS API (only US locations are supported).")] # Extract forecast URL from the response properties = points_data.get("properties", {}) forecast_url = properties.get("forecast") if not forecast_url: return [types.TextContent(type="text", text="Failed to get forecast URL from grid point data")] # Get the forecast forecast_data = await make_nws_request(client, forecast_url) if not forecast_data: return [types.TextContent(type="text", text="Failed to retrieve forecast data")] # Format the forecast periods periods = forecast_data.get("properties", {}).get("periods", []) if not periods: return [types.TextContent(type="text", text="No forecast periods available")] # Format each period into a concise string formatted_forecast = [] for period in periods: forecast_text = ( f"{period.get('name', 'Unknown')}:\n" f"Temperature: {period.get('temperature', 'Unknown')}°{period.get('temperatureUnit', 'F')}\n" f"Wind: {period.get('windSpeed', 'Unknown')} {period.get('windDirection', '')}\n" f"{period.get('shortForecast', 'No forecast available')}\n" "---" ) formatted_forecast.append(forecast_text) forecast_text = f"Forecast for {latitude}, {longitude}:\n\n" + "\n".join(formatted_forecast) return [types.TextContent( type="text", text=forecast_text )] else: raise ValueError(f"Unknown tool: {name}") async def main(): # Run the server using stdin/stdout streams async with mcp.server.stdio.stdio_server() as (read_stream, write_stream): await server.run( read_stream, write_stream, InitializationOptions( server_name="weather", server_version="0.1.0", capabilities=server.get_capabilities( notification_options=NotificationOptions(), experimental_capabilities={}, ), ), ) if __name__ == "__main__": asyncio.run(main())