OpenWeatherMap MCP Server

Instructions

Implementation Reference

• src/main.ts:450-516 (registration)

  Registration of the 'get-weather-alerts' tool using server.addTool, including inline handler (execute function) that fetches alerts using OpenWeather client, formats as JSON, and handles errors.

  server.addTool({
    name: "get-weather-alerts",
    description: "Get active weather alerts and warnings",
    parameters: getWeatherAlertsSchema,
    execute: async (args, { session, log }) => {
      try {
        log.info("Getting weather alerts", { 
          location: args.location
        });
        
        // Get OpenWeather client
        const client = getOpenWeatherClient(session as SessionData | undefined);
        
        // Configure client for this request
        configureClientForLocation(client, args.location);
        
        // Fetch alerts data
        const alertsData = await client.getAlerts();
        
        log.info("Successfully retrieved weather alerts", { 
          location: args.location,
          alerts_count: alertsData.length
        });
        
        // Format the response
        const formattedAlerts = JSON.stringify({
          location: args.location,
          alerts_count: alertsData.length,
          alerts: alertsData.map(alert => ({
            sender: alert.sender_name,
            event: alert.event,
            start_time: new Date(alert.start * 1000).toISOString(),
            end_time: new Date(alert.end * 1000).toISOString(),
            description: alert.description,
            tags: alert.tags,
            severity: alert.tags.includes('severe') || alert.tags.includes('extreme') ? 'High' : 
                     alert.tags.includes('moderate') ? 'Medium' : 'Low'
          }))
        }, null, 2);
        
        return {
          content: [
            {
              type: "text",
              text: formattedAlerts
            }
          ]
        };
      } catch (error) {
        log.error("Failed to get weather alerts", { 
          error: error instanceof Error ? error.message : 'Unknown error' 
        });
        
        // Provide helpful error messages
        if (error instanceof Error) {
          if (error.message.includes('city not found')) {
            throw new Error(`Location "${args.location}" not found. Please check the spelling or try using coordinates.`);
          }
          if (error.message.includes('Invalid API key')) {
            throw new Error('Invalid OpenWeatherMap API key. Please check your configuration.');
          }
        }
        
        throw new Error(`Failed to get weather alerts: ${error instanceof Error ? error.message : 'Unknown error'}`);
      }
    }
  });

• src/main.ts:454-515 (handler)

  The execute handler function for get-weather-alerts: configures OpenWeather client for location, calls client.getAlerts(), formats alerts data into JSON with details like sender, event, times, description, tags, severity, and returns as text content.

  execute: async (args, { session, log }) => {
    try {
      log.info("Getting weather alerts", { 
        location: args.location
      });
      
      // Get OpenWeather client
      const client = getOpenWeatherClient(session as SessionData | undefined);
      
      // Configure client for this request
      configureClientForLocation(client, args.location);
      
      // Fetch alerts data
      const alertsData = await client.getAlerts();
      
      log.info("Successfully retrieved weather alerts", { 
        location: args.location,
        alerts_count: alertsData.length
      });
      
      // Format the response
      const formattedAlerts = JSON.stringify({
        location: args.location,
        alerts_count: alertsData.length,
        alerts: alertsData.map(alert => ({
          sender: alert.sender_name,
          event: alert.event,
          start_time: new Date(alert.start * 1000).toISOString(),
          end_time: new Date(alert.end * 1000).toISOString(),
          description: alert.description,
          tags: alert.tags,
          severity: alert.tags.includes('severe') || alert.tags.includes('extreme') ? 'High' : 
                   alert.tags.includes('moderate') ? 'Medium' : 'Low'
        }))
      }, null, 2);
      
      return {
        content: [
          {
            type: "text",
            text: formattedAlerts
          }
        ]
      };
    } catch (error) {
      log.error("Failed to get weather alerts", { 
        error: error instanceof Error ? error.message : 'Unknown error' 
      });
      
      // Provide helpful error messages
      if (error instanceof Error) {
        if (error.message.includes('city not found')) {
          throw new Error(`Location "${args.location}" not found. Please check the spelling or try using coordinates.`);
        }
        if (error.message.includes('Invalid API key')) {
          throw new Error('Invalid OpenWeatherMap API key. Please check your configuration.');
        }
      }
      
      throw new Error(`Failed to get weather alerts: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

• src/schemas.ts:50-52 (schema)

  Zod validation schema defining the input parameter 'location' (string: city name or coordinates) for the get-weather-alerts tool.

  export const getWeatherAlertsSchema = z.object({
    location: z.string().describe("City name (e.g., 'New York') or coordinates (e.g., 'lat,lon')"),
  });