get-alerts

Instructions

Implementation Reference

• src/index.ts:85-109 (handler)

  The async handler function that fetches weather alerts from the NWS API for the specified state, formats them using formatAlert, and returns formatted text content.

  async ({ state }) => {
      const stateCode = state.toUpperCase();
      const alertsUrl = `${NWS_API_BASE}/alerts?area=${stateCode}`;
      const alertsData = await fetchJson<AlertsResponse>(alertsUrl, {
          Accept: "application/geo+json",
      });
  
      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);
      return {
          content: [{ type: "text", text: `Active alerts for ${stateCode}:\n\n${formattedAlerts.join("\n")}` }],
      };
  }

• src/index.ts:82-84 (schema)

  Input schema for the get-alerts tool, defining the 'state' parameter as a 2-letter string.

  {
      state: z.string().length(2).describe("Two-letter state code (e.g. CA, NY)"),
  },

• src/index.ts:79-110 (registration)

  Registration of the 'get-alerts' tool using server.tool, including name, description, input schema, and handler function.

  server.tool(
      "get-alerts",
      "Get weather alerts for a state",
      {
          state: z.string().length(2).describe("Two-letter state code (e.g. CA, NY)"),
      },
      async ({ state }) => {
          const stateCode = state.toUpperCase();
          const alertsUrl = `${NWS_API_BASE}/alerts?area=${stateCode}`;
          const alertsData = await fetchJson<AlertsResponse>(alertsUrl, {
              Accept: "application/geo+json",
          });
  
          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);
          return {
              content: [{ type: "text", text: `Active alerts for ${stateCode}:\n\n${formattedAlerts.join("\n")}` }],
          };
      }
  );

• src/index.ts:42-52 (helper)

  Helper function to format a single weather alert feature into a multi-line string.

  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");
  }

• src/index.ts:20-29 (helper)

  Shared helper function used to fetch and parse JSON from APIs, with error handling.

  async function fetchJson<T>(url: string, headers: Record<string, string> = {}): Promise<T | null> {
      try {
          const response = await fetch(url, { headers: { "User-Agent": USER_AGENT, ...headers } });
          if (!response.ok) throw new Error(`HTTP error ${response.status}`);
          return (await response.json()) as T;
      } catch (err) {
          console.error("Fetch error:", err);
          return null;
      }
  }