Display "completions not supported" for resource templates which do not support completions.

client/src/components/ResourcesTab.tsx

@@ -248,6 +248,18 @@ const ResourcesTab = ({
                           id={key}
                           placeholder={`Enter ${key}`}
                           value={templateValues[key] || ""}
+                          emptyMessage={
+                            <div className="px-6">
+                              This resource does not support{" "}
+                              <a
+                                href="https://modelcontextprotocol.io/specification/2025-03-26/server/utilities/completion"
+                                target="_blank"
+                              >
+                                completions
+                              </a>
+                              .
+                            </div>
+                          }
                           onChange={(value) =>
                             handleTemplateValueChange(key, value)
                           }

client/src/components/__tests__/combobox.tsx

@@ -0,0 +1,41 @@
+import { render, screen, fireEvent } from "@testing-library/react";
+import "@testing-library/jest-dom";
+import { describe, it } from "@jest/globals";
+import { Combobox } from "../ui/combobox";
+
+describe("combobox", () => {
+  it("should render custom empty message", async () => {
+    const customMessage = (
+      <div data-testid="custom-empty">Custom empty message</div>
+    );
+    render(
+      <Combobox
+        value=""
+        onChange={() => {}}
+        onInputChange={() => {}}
+        options={[]}
+        emptyMessage={customMessage}
+      />,
+    );
+
+    fireEvent.click(screen.getByRole("combobox"));
+
+    expect(await screen.findByTestId("custom-empty")).toBeInTheDocument();
+    expect(screen.getByText("Custom empty message")).toBeInTheDocument();
+  });
+
+  it("should render default empty message", async () => {
+    render(
+      <Combobox
+        value=""
+        onChange={() => {}}
+        onInputChange={() => {}}
+        options={[]}
+      />,
+    );
+
+    fireEvent.click(screen.getByRole("combobox"));
+
+    expect(await screen.findByText("No results found.")).toBeInTheDocument();
+  });
+});

client/src/components/ui/combobox.tsx

@@ -21,7 +21,7 @@ interface ComboboxProps {
   onInputChange: (value: string) => void;
   options: string[];
   placeholder?: string;
-  emptyMessage?: string;
+  emptyMessage?: string | React.ReactNode;
   id?: string;
 }
 

client/src/index.css

@@ -91,7 +91,7 @@ h1 {
     --muted-foreground: 215 20.2% 65.1%;
     --accent: 217.2 32.6% 17.5%;
     --accent-foreground: 210 40% 98%;
-    --destructive: 0 62.8% 30.6%;
+    --destructive: 0 81.8% 54.6%;
     --destructive-foreground: 210 40% 98%;
     --border: 217.2 24% 24%;
     --input: 217.2 24% 24%;