show server stderr in inspector UI

client/src/lib/notificationTypes.ts

@@ -0,0 +1,19 @@
+import {
+  ClientNotificationSchema,
+  NotificationSchema as BaseNotificationSchema,
+} from "@modelcontextprotocol/sdk/types.js";
+import { z } from "zod";
+
+export const StderrNotificationSchema = BaseNotificationSchema.extend({
+  method: z.literal("notifications/stderr"),
+  params: z.object({
+    content: z.string(),
+  }),
+});
+
+export const NotificationSchema = ClientNotificationSchema.or(
+  StderrNotificationSchema,
+);
+
+export type StdErrNotification = z.infer<typeof StderrNotificationSchema>;
+export type Notification = z.infer<typeof NotificationSchema>;