@h1deya/mcp-server-weather
Version:
MCP server for weather forecast and severe weather alerts in the US
226 lines (225 loc) • 8.02 kB
JavaScript
// Ref: https://modelcontextprotocol.io/quickstart
import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { CallToolRequestSchema, ListToolsRequestSchema, } from "@modelcontextprotocol/sdk/types.js";
import { z } from "zod";
const NWS_API_BASE = "https://api.weather.gov";
const USER_AGENT = "weather-app/1.0";
// Define Zod schemas for validation
const AlertsArgumentsSchema = z.object({
state: z.string().length(2),
});
const ForecastArgumentsSchema = z.object({
latitude: z.number().min(-90).max(90),
longitude: z.number().min(-180).max(180),
});
// Create server instance
const server = new Server({
name: "weather",
version: "1.0.0",
}, {
capabilities: {
tools: {},
},
});
// List available tools
server.setRequestHandler(ListToolsRequestSchema, async () => {
return {
tools: [
{
name: "get-alerts",
description: "Get weather alerts for a US state",
inputSchema: {
type: "object",
properties: {
state: {
type: "string",
description: "Two-letter US state code (e.g. CA, NY)",
},
},
required: ["state"],
},
},
{
name: "get-forecast",
description: "Get weather forecast for a location in the US",
inputSchema: {
type: "object",
properties: {
latitude: {
type: "number",
description: "Latitude of the location",
},
longitude: {
type: "number",
description: "Longitude of the location",
},
},
required: ["latitude", "longitude"],
},
},
],
};
});
// Helper function for making NWS API requests
async function makeNWSRequest(url) {
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());
}
catch (error) {
console.error("Error making NWS request:", error);
return null;
}
}
// Format alert data
function formatAlert(feature) {
const props = feature.properties;
return [
`Event: ${props.event || "Unknown"}`,
`Area: ${props.areaDesc || "Unknown"}`,
`Severity: ${props.severity || "Unknown"}`,
`Status: ${props.status || "Unknown"}`,
`Headline: ${props.headline || "No headline"}`,
"---",
].join("\n");
}
// Handle tool execution
server.setRequestHandler(CallToolRequestSchema, async (request) => {
const { name, arguments: args } = request.params;
try {
if (name === "get-alerts") {
const { state } = AlertsArgumentsSchema.parse(args);
const stateCode = state.toUpperCase();
const alertsUrl = `${NWS_API_BASE}/alerts?area=${stateCode}`;
const alertsData = await makeNWSRequest(alertsUrl);
if (!alertsData) {
return {
content: [
{
type: "text",
text: "Failed to retrieve alerts data",
},
],
};
}
const features = alertsData.features || [];
if (features.length === 0) {
return {
content: [
{
type: "text",
text: `No active alerts for ${stateCode}`,
},
],
};
}
const formattedAlerts = features.map(formatAlert).slice(0, 20); // only take the first 20 alerts;
const alertsText = `Active alerts for ${stateCode}:\n\n${formattedAlerts.join("\n")}`;
return {
content: [
{
type: "text",
text: alertsText,
},
],
};
}
else if (name === "get-forecast") {
const { latitude, longitude } = ForecastArgumentsSchema.parse(args);
// Get grid point data
const pointsUrl = `${NWS_API_BASE}/points/${latitude.toFixed(4)},${longitude.toFixed(4)}`;
const pointsData = await makeNWSRequest(pointsUrl);
if (!pointsData) {
return {
content: [
{
type: "text",
text: `Failed to retrieve grid point data for coordinates: ${latitude}, ${longitude}. This location may not be supported by the NWS API (only US locations are supported).`,
},
],
};
}
const forecastUrl = pointsData.properties?.forecast;
if (!forecastUrl) {
return {
content: [
{
type: "text",
text: "Failed to get forecast URL from grid point data",
},
],
};
}
// Get forecast data
const forecastData = await makeNWSRequest(forecastUrl);
if (!forecastData) {
return {
content: [
{
type: "text",
text: "Failed to retrieve forecast data",
},
],
};
}
const periods = forecastData.properties?.periods || [];
if (periods.length === 0) {
return {
content: [
{
type: "text",
text: "No forecast periods available",
},
],
};
}
// Format forecast periods
const formattedForecast = periods.map((period) => [
`${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",
text: forecastText,
},
],
};
}
else {
throw new Error(`Unknown tool: ${name}`);
}
}
catch (error) {
if (error instanceof z.ZodError) {
throw new Error(`Invalid arguments: ${error.errors
.map((e) => `${e.path.join(".")}: ${e.message}`)
.join(", ")}`);
}
throw error;
}
});
// Start the server
async function main() {
const transport = new StdioServerTransport();
await server.connect(transport);
console.error("Weather MCP Server running on stdio");
}
main().catch((error) => {
console.error("Fatal error in main():", error);
process.exit(1);
});