dk_weather_forecast

Instructions

Implementation Reference

• src/servers/danish-weather.js:152-205 (handler)

  The dk_weather_forecast tool implementation, including schema definition and request handling logic.

  server.tool(
    "dk_weather_forecast",
    "Get hourly or daily weather forecast for a location in Denmark. Uses DMI HARMONIE 2km model for the first 2.5 days, then ECMWF for up to 16 days.",
    {
      location: z.string().describe("Danish city name, postal code, or lat,lon coordinates"),
      days: z.number().min(1).max(16).optional().describe("Forecast days (default 3, max 16)"),
      mode: z.enum(["hourly", "daily"]).optional().describe("Hourly detail or daily summary (default: daily)"),
    },
    async ({ location, days, mode }) => {
      try {
        const loc = await getLocation(location);
        const forecastDays = days || 3;
        const isHourly = mode === "hourly";
  
        const params = { latitude: loc.lat, longitude: loc.lon, forecast_days: forecastDays };
        if (isHourly) {
          params.hourly = "temperature_2m,apparent_temperature,precipitation,weather_code,wind_speed_10m,wind_gusts_10m,cloud_cover";
        } else {
          params.daily = "weather_code,temperature_2m_max,temperature_2m_min,apparent_temperature_max,apparent_temperature_min,sunrise,sunset,precipitation_sum,wind_speed_10m_max,wind_gusts_10m_max,wind_direction_10m_dominant";
        }
  
        const data = await openMeteoFetch(params);
        const lines = [`## ${loc.name} — ${forecastDays}-Day Forecast\n`];
  
        if (isHourly) {
          const h = data.hourly;
          for (let i = 0; i < h.time.length; i++) {
            const t = new Date(h.time[i]);
            const time = t.toLocaleString("da-DK", { timeZone: "Europe/Copenhagen", weekday: "short", day: "numeric", month: "short", hour: "2-digit", minute: "2-digit" });
            const wx = WMO_CODES[h.weather_code[i]] || "";
            lines.push(`**${time}:** ${h.temperature_2m[i]}°C (feels ${h.apparent_temperature[i]}°C), ${wx}, wind ${h.wind_speed_10m[i]} km/h, precip ${h.precipitation[i]} mm`);
          }
        } else {
          const d = data.daily;
          for (let i = 0; i < d.time.length; i++) {
            const date = new Date(d.time[i]);
            const day = date.toLocaleDateString("da-DK", { timeZone: "Europe/Copenhagen", weekday: "long", day: "numeric", month: "long" });
            const wx = WMO_CODES[d.weather_code[i]] || "";
            const sunrise = d.sunrise[i]?.split("T")[1] || "";
            const sunset = d.sunset[i]?.split("T")[1] || "";
            lines.push(`### ${day}`);
            lines.push(`${wx} | ${d.temperature_2m_min[i]}°C to ${d.temperature_2m_max[i]}°C (feels ${d.apparent_temperature_min[i]}° to ${d.apparent_temperature_max[i]}°)`);
            lines.push(`Wind: up to ${d.wind_speed_10m_max[i]} km/h (gusts ${d.wind_gusts_10m_max[i]} km/h) from ${d.wind_direction_10m_dominant[i]}°`);
            lines.push(`Precipitation: ${d.precipitation_sum[i]} mm | ☀️ ${sunrise} — ${sunset}\n`);
          }
        }
  
        lines.push(`*DMI HARMONIE 2km model via Open-Meteo*`);
        return { content: [{ type: "text", text: lines.join("\n") }] };
      } catch (err) {
        return { content: [{ type: "text", text: `Error: ${err.message}` }], isError: true };
      }
    }
  );