MCP Weather

Instructions

Implementation Reference

• src/tools/WeatherDailyTool.ts:40-130 (handler)

  Main handler function for 'weather-get_daily' tool. Validates input with Zod, fetches location key and daily forecast from AccuWeather API, handles errors, and formats forecast data into text content array.

  export async function handler(
    args: { [x: string]: any },
    extra: RequestHandlerExtra<any, any>
  ): Promise<{ content: TextContent[] }> {
    // Validate args using the Zod schema
    let validatedArgs: z.infer<typeof inputSchema>;
    try {
      validatedArgs = inputSchema.parse(args);
    } catch (error) {
      if (error instanceof z.ZodError) {
        const errorMessages = error.errors
          .map((e) => `${e.path.join('.')}: ${e.message}`)
          .join(', ');
        return { content: [{ type: 'text', text: `Invalid input: ${errorMessages}` }] };
      }
      return { content: [{ type: 'text', text: 'An unexpected error occurred during input validation.' }] };
    }
  
    const { location, days = 5, units = "metric" } = validatedArgs;
    const apiKey = process.env.ACCUWEATHER_API_KEY;
    if (!apiKey) {
      return { content: [{ type: 'text', text: 'Error: AccuWeather API key not configured' }] };
    }
  
    try {
      // Step 1: Get location key
      const locationUrl = `https://dataservice.accuweather.com/locations/v1/cities/search?apikey=${apiKey}&q=${encodeURIComponent(location)}`;
      const locationResp = await axios.get(locationUrl);
  
      if (!locationResp.data || locationResp.data.length === 0) {
        return { content: [{ type: 'text', text: `No location found for: ${location}` }] };
      }
  
      const locationKey = locationResp.data[0].Key;
  
      // Get valid forecast period (AccuWeather supports 1, 5, 10, or 15 days)
      let forecastDays = 5; // default
      if (days === 1) forecastDays = 1;
      else if (days <= 5) forecastDays = 5;
      else if (days <= 10) forecastDays = 10;
      else forecastDays = 15;
  
      // Step 2: Get forecast with location key
      const forecastUrl = `https://dataservice.accuweather.com/forecasts/v1/daily/${forecastDays}day/${locationKey}?apikey=${apiKey}&metric=${units === "metric" ? "true" : "false"}`;
      const forecastResp = await axios.get(forecastUrl);
      const data = forecastResp.data;
  
      if (!data || !data.DailyForecasts || !Array.isArray(data.DailyForecasts) || data.DailyForecasts.length === 0) {
        return {
          content: [{ type: 'text', text: `No daily forecast data available for location: ${location}` }]
        };
      }
  
      const degreeSymbol = "°";
      const unitSymbol = units === "metric" ? "C" : "F";
  
      const content: TextContent[] = data.DailyForecasts.map((day: any) => {
        const date = new Date(day.Date);
        const formattedDate = date.toLocaleDateString('en-US', { 
          weekday: 'long', 
          year: 'numeric', 
          month: 'short', 
          day: 'numeric' 
        });
        
        return {
          type: 'text',
          text: `${formattedDate}: ${day.Temperature.Minimum.Value}${degreeSymbol}${unitSymbol} to ${day.Temperature.Maximum.Value}${degreeSymbol}${unitSymbol}, Day: ${day.Day.IconPhrase}, Night: ${day.Night.IconPhrase}${day.Day.HasPrecipitation || day.Night.HasPrecipitation ? ' (Precipitation expected)' : ''}`
        };
      });
  
      return { content };
    } catch (error) {
      console.error("WeatherDailyTool handler error:", error);
      let errorMessage = "An error occurred while fetching weather data.";
  
      if (axios.isAxiosError(error)) {
        if (error.response?.status === 401) {
          errorMessage = "Invalid AccuWeather API key. Please check your credentials.";
        } else if (error.response?.status === 404) {
          errorMessage = `Location not found: ${location}`;
        } else if (error.response) {
          errorMessage = `AccuWeather API error (${error.response.status}): ${error.response.data?.Message || error.message}`;
        } else if (error.request) {
          errorMessage = "Network error: Unable to connect to AccuWeather API.";
        }
      }
  
      return { content: [{ type: 'text', text: errorMessage }] };
    }
  }

• src/tools/WeatherDailyTool.ts:16-37 (schema)

  JSON schema definition for the tool's input parameters, used for registration and validation.

  export const inputJsonSchema = {
    type: "object",
    description: "Parameters for the daily weather-forecast tool",
    properties: {
      location: {
        type: "string",
        description: "The location to fetch the daily forecast for",
      },
      days: {
        type: "number",
        description: "Number of days to forecast (1, 5, 10, or 15). Default is 5.",
        enum: [1, 5, 10, 15]
      },
      units: {
        type: "string",
        description: "Temperature unit system (metric for Celsius, imperial for Fahrenheit). Default is metric.",
        enum: ["metric", "imperial"]
      }
    },
    required: ["location"],
    additionalProperties: false,
  };

• src/tools/WeatherDailyTool.ts:7-14 (schema)

  Zod schema for runtime input validation within the handler.

  export const inputShape = {
    location: z.string().min(1, "Location must be at least 1 character"),
    days: z.number().int().min(1).max(15).default(5).optional().describe("Number of days for forecast (1-15)"),
    units: z.enum(["imperial", "metric"]).default("metric").optional().describe("Temperature unit system")
  };
  
  export const inputSchema = z.object(inputShape).describe("Get daily weather forecast");

• src/index.ts:31-54 (registration)

  Tool definition object including name, description, and input schema, used for registration.

  const dailyWeatherTool: Tool = {
    name: "weather-get_daily",
    description: "Get daily weather forecast for up to 15 days",
    inputSchema: {
      type: "object",
      properties: {
        location: {
          type: "string",
          description: "The city or location for which to retrieve the weather forecast."
        },
        days: {
          type: "number",
          description: "Number of days to forecast (1, 5, 10, or 15). Default is 5.",
          enum: [1, 5, 10, 15]
        },
        units: {
          type: "string",
          description: "Temperature unit system (metric for Celsius, imperial for Fahrenheit). Default is metric.",
          enum: ["metric", "imperial"]
        }
      },
      required: ["location"]
    }
  };

• src/index.ts:83-86 (registration)

  Dispatch logic in CallToolRequestSchema handler that routes to the dailyHandler when tool name matches.

  if (request.params.name === "weather-get_hourly") {
    return await hourlyHandler(args, {} as RequestHandlerExtra<any, any>);
  } else if (request.params.name === "weather-get_daily") {
    return await dailyHandler(args, {} as RequestHandlerExtra<any, any>);