Weather MCP Server

Instructions

Implementation Reference

• src/weather-service.ts:49-65 (handler)

  The core handler function that implements the logic for the get_weather_alerts tool, filtering mock weather alerts based on location.

  async getWeatherAlerts(location?: string): Promise<WeatherAlert[]> {
    if (!location) {
      return mockWeatherAlerts;
    }
    
    const normalizedLocation = this.normalizeLocation(location);
    const locationName = mockWeatherData[normalizedLocation]?.location || location;
    
    return mockWeatherAlerts.filter(alert => 
      alert.areas.some(area => 
        area.toLowerCase().includes(locationName.toLowerCase()) ||
        locationName.toLowerCase().includes(area.toLowerCase()) ||
        area.toLowerCase().includes(normalizedLocation) ||
        normalizedLocation.includes(area.toLowerCase())
      )
    );
  }

• src/index.ts:72-84 (schema)

  JSON Schema definition for the input parameters of the get_weather_alerts tool.

  {
    name: 'get_weather_alerts',
    description: 'Get weather alert information',
    inputSchema: {
      type: 'object',
      properties: {
        location: {
          type: 'string',
          description: 'Location name (optional, if not provided, get all alerts)',
        },
      },
    },
  },

• src/index.ts:143-154 (registration)

  Registration of the tool call handler for get_weather_alerts in the main MCP stdio server.

  case 'get_weather_alerts': {
    const { location } = args as { location?: string };
    const alerts = await this.weatherService.getWeatherAlerts(location);
    return {
      content: [
        {
          type: 'text',
          text: JSON.stringify(alerts, null, 2),
        },
      ],
    };
  }

• src/types.ts:30-39 (schema)

  TypeScript interface defining the WeatherAlert type used for output validation.

  export interface WeatherAlert {
    id: string;
    type: string;
    severity: 'minor' | 'moderate' | 'severe' | 'extreme';
    title: string;
    description: string;
    areas: string[];
    startTime: string;
    endTime: string;
  } 

• src/mock-data.ts:339-400 (helper)

  Mock data array of WeatherAlert objects used by the handler to provide sample weather alerts.

  export const mockWeatherAlerts: WeatherAlert[] = [
    {
      id: 'hk-typhoon-001',
      type: 'Typhoon',
      severity: 'severe',
      title: 'Typhoon Warning Signal No. 8',
      description: 'Strong winds and heavy rain expected. Stay indoors and avoid unnecessary travel. Public transport may be suspended.',
      areas: ['Hong Kong Island', 'Kowloon', 'New Territories'],
      startTime: new Date().toISOString(),
      endTime: new Date(Date.now() + 12 * 60 * 60 * 1000).toISOString()
    },
    {
      id: 'tokyo-heatwave-001',
      type: 'Heat Wave',
      severity: 'moderate',
      title: 'High Temperature Advisory',
      description: 'Temperatures may exceed 35°C. Stay hydrated and avoid prolonged outdoor activities during peak hours.',
      areas: ['Tokyo Metropolitan Area', 'Chiba', 'Saitama'],
      startTime: new Date().toISOString(),
      endTime: new Date(Date.now() + 24 * 60 * 60 * 1000).toISOString()
    },
    {
      id: 'osaka-thunderstorm-001',
      type: 'Thunderstorm',
      severity: 'moderate',
      title: 'Severe Thunderstorm Warning',
      description: 'Heavy rain, lightning, and strong winds expected. Avoid outdoor activities and seek shelter.',
      areas: ['Osaka Prefecture', 'Kyoto', 'Nara'],
      startTime: new Date(Date.now() + 2 * 60 * 60 * 1000).toISOString(),
      endTime: new Date(Date.now() + 8 * 60 * 60 * 1000).toISOString()
    },
    {
      id: 'sapporo-snow-001',
      type: 'Snow',
      severity: 'minor',
      title: 'Late Season Snow Advisory',
      description: 'Unexpected late spring snowfall possible. Roads may become slippery, drive with caution.',
      areas: ['Sapporo City', 'Hokkaido Central'],
      startTime: new Date(Date.now() + 6 * 60 * 60 * 1000).toISOString(),
      endTime: new Date(Date.now() + 18 * 60 * 60 * 1000).toISOString()
    },
    {
      id: 'london-flood-001',
      type: 'Flood',
      severity: 'moderate',
      title: 'Flood Warning',
      description: 'Heavy rainfall may cause flooding in low-lying areas. Avoid driving through flooded roads.',
      areas: ['Thames Valley', 'South London', 'Surrey'],
      startTime: new Date().toISOString(),
      endTime: new Date(Date.now() + 6 * 60 * 60 * 1000).toISOString()
    },
    {
      id: 'fukuoka-typhoon-001',
      type: 'Typhoon',
      severity: 'severe',
      title: 'Typhoon Approach Warning',
      description: 'Typhoon approaching southern Japan. Prepare for strong winds, heavy rain, and possible power outages.',
      areas: ['Fukuoka Prefecture', 'Kumamoto', 'Kagoshima'],
      startTime: new Date(Date.now() + 4 * 60 * 60 * 1000).toISOString(),
      endTime: new Date(Date.now() + 20 * 60 * 60 * 1000).toISOString()
    }
  ];