Weather MCP Server

import { z } from "zod"; const NWS_API_BASE = "https://api.weather.gov"; const USER_AGENT = "weather-app/1.0"; // Helper function for making NWS API requests export async function makeNWSRequest<T>(url: string): Promise<T | null> { const headers = { "User-Agent": USER_AGENT, Accept: "application/geo+json", }; try { const response = await fetch(url, { headers }); if (!response.ok) { throw new Error(`HTTP error! status: ${response.status}`); } return (await response.json()) as T; } catch (error) { console.error("Error making NWS request:", error); return null; } } export interface AlertFeature { properties: { event?: string; areaDesc?: string; severity?: string; status?: string; headline?: string; }; } // Format alert data export function formatAlert(feature: AlertFeature): string { const props = feature.properties; return [ `Event: ${props.event || "Unknown"}`, `Area: ${props.areaDesc || "Unknown"}`, `Severity: ${props.severity || "Unknown"}`, `Status: ${props.status || "Unknown"}`, `Headline: ${props.headline || "No headline"}`, "---", ].join("\n"); } export interface ForecastPeriod { name?: string; temperature?: number; temperatureUnit?: string; windSpeed?: string; windDirection?: string; shortForecast?: string; } export interface AlertsResponse { features: AlertFeature[]; } export interface PointsResponse { properties: { forecast?: string; }; } export interface ForecastResponse { properties: { periods: ForecastPeriod[]; }; } // Weather tool implementations export async function getAlerts(state: string) { const stateCode = state.toUpperCase(); const alertsUrl = `${NWS_API_BASE}/alerts?area=${stateCode}`; const alertsData = await makeNWSRequest<AlertsResponse>(alertsUrl); if (!alertsData) { return { content: [ { type: "text" as const, text: "Failed to retrieve alerts data", }, ], }; } const features = alertsData.features || []; if (features.length === 0) { return { content: [ { type: "text" as const, text: `No active alerts for ${stateCode}`, }, ], }; } const formattedAlerts = features.map(formatAlert); const alertsText = `Active alerts for ${stateCode}:\n\n${formattedAlerts.join("\n")}`; return { content: [ { type: "text" as const, text: alertsText, }, ], }; } export async function getForecast(latitude: number, longitude: number) { // Get grid point data const pointsUrl = `${NWS_API_BASE}/points/${latitude.toFixed(4)},${longitude.toFixed(4)}`; const pointsData = await makeNWSRequest<PointsResponse>(pointsUrl); if (!pointsData) { return { content: [ { type: "text" as const, text: `Failed to retrieve grid point data for coordinates: ${latitude}, ${longitude}. This location may not be supported by the NWS API (only US locations are supported).`, }, ], }; } const forecastUrl = pointsData.properties?.forecast; if (!forecastUrl) { return { content: [ { type: "text" as const, text: "Failed to get forecast URL from grid point data", }, ], }; } // Get forecast data const forecastData = await makeNWSRequest<ForecastResponse>(forecastUrl); if (!forecastData) { return { content: [ { type: "text" as const, text: "Failed to retrieve forecast data", }, ], }; } const periods = forecastData.properties?.periods || []; if (periods.length === 0) { return { content: [ { type: "text" as const, text: "No forecast periods available", }, ], }; } // Format forecast periods const formattedForecast = periods.map((period: ForecastPeriod) => [ `${period.name || "Unknown"}:`, `Temperature: ${period.temperature || "Unknown"}°${period.temperatureUnit || "F"}`, `Wind: ${period.windSpeed || "Unknown"} ${period.windDirection || ""}`, `${period.shortForecast || "No forecast available"}`, "---", ].join("\n"), ); const forecastText = `Forecast for ${latitude}, ${longitude}:\n\n${formattedForecast.join("\n")}`; return { content: [ { type: "text" as const, text: forecastText, }, ], }; } // Validation schemas export const alertsSchema = z.object({ state: z.string().length(2).describe("Two-letter state code (e.g. CA, NY)"), }); export const forecastSchema = z.object({ latitude: z.number().min(-90).max(90).describe("Latitude of the location"), longitude: z.number().min(-180).max(180).describe("Longitude of the location"), });