Merge pull request #9 from modelcontextprotocol/ochafik/update-packages

update simple-examples (add "raw" no-sdk example)

.gitignore

@@ -1,3 +1,6 @@
 .DS_Store
 dist/
 node_modules/
+package-lock.json
+yarn.lock
+.vscode/

README.md

@@ -5,15 +5,16 @@ This repo contains the SDK and [specification](./specification/draft/apps.mdx) f
 MCP Apps are proposed standard inspired by [MCP-UI](https://mcpui.dev/) and [OpenAI's Apps SDK](https://developers.openai.com/apps-sdk/) to allow MCP Servers to display interactive UI elements in conversational MCP clients / chatbots.
 
 This repo provides:
+
+- [specification/draft/apps.mdx](./specification/draft/apps.mdx): The Draft Extension Specification. It's still... in flux! Feedback welcome! (also see discussions in [SEP-1865](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1865)).
+
 - [types.ts](./src/types.ts): Types of JSON-RPC messages used to communicate between Apps & their host
   - Note that MCP Apps also use some standard MCP messages (e.g. `tools/call` for the App to trigger actions on its originating Server - these calls are proxied through the Host), but these types are the additional messages defined by the extension
-  
 - [examples/simple-example](./examples/simple-example): Example Server + Apps
-  - [server.ts](./examples/simple-server/server.ts): MCP server with two tools that declare UI resources of Apps to be show in the chat when called
+  - [server.ts](./examples/simple-server/server.ts): MCP server with three tools that declare UI resources of Apps to be show in the chat when called
   - [ui-react.tsx](./examples/simple-server/src/ui-react.tsx): React App returned by the `create-ui-react` tool shows how to use the `useApp` hook to register MCP callbacks
   - [ui-vanilla.tsx](./examples/simple-server/src/ui-vanilla.ts): vanilla App returned by the `create-ui-vanilla`
-  
+  - [ui-raw.tsx](./examples/simple-server/src/ui-raw.ts): same as vanilla App but doesn't use the SDK runtime (just its types)
-- [specification/draft/apps.mdx](./specification/draft/apps.mdx): The Draft Extension Specification. It's still... in flux! Feedback welcome! (also see discussions in [SEP-1865](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1865)).
 
 - [message-transport](./src/message-transport.ts): `PostMessageTransport` class that uses `postMessage` to exchange JSON-RPC messages between windows / iframes
 

build.bun.ts

@@ -8,20 +8,28 @@ const isDevelopment = Bun.env.NODE_ENV === "development";
 
 // Build all JavaScript/TypeScript files
 function buildJs(entrypoint: string, opts: Record<string, any> = {}) {
-    return Bun.build({
+  return Bun.build({
-        entrypoints: [entrypoint],
+    entrypoints: [entrypoint],
-        outdir: "dist",
+    outdir: "dist",
-        target: "browser",
+    target: "browser",
-        minify: !isDevelopment,
+    minify: !isDevelopment,
-        ...(isDevelopment ? {
+    ...(isDevelopment
-            sourcemap: "inline",
+      ? {
-        } : {}),
+          sourcemap: "inline",
-        ...opts
+        }
-    })
+      : {}),
+    ...opts,
+  });
 }
 
 await Promise.all([
   buildJs("src/app.ts", { outdir: "dist/src" }),
-  buildJs("src/app-bridge.ts", { outdir: "dist/src", external: ["@modelcontextprotocol/sdk"] }),
+  buildJs("src/app-bridge.ts", {
-  buildJs("src/react/index.tsx", { outdir: "dist/src/react", external: ["react", "react-dom"]}),
+    outdir: "dist/src",
-])
+    external: ["@modelcontextprotocol/sdk"],
+  }),
+  buildJs("src/react/index.tsx", {
+    outdir: "dist/src/react",
+    external: ["react", "react-dom"],
+  }),
+]);

examples/simple-server/package.json

@@ -4,15 +4,13 @@
   "private": true,
   "type": "module",
   "scripts": {
-    "dev": "vite",
+    "build:uis": "rm -rf dist && concurrently 'UI=ui-raw.html vite build' 'UI=ui-vanilla.html vite build' 'UI=ui-react.html vite build'",
-    "build": "rm -rf dist && VITE_ENTRY=ui-vanilla vite build && VITE_ENTRY=ui-react vite build",
-    "preview": "vite preview",
     "server": "bun server.ts",
-    "start": "npm run build && npm run server"
+    "start": "npm run build:uis && npm run server"
   },
   "dependencies": {
-    "@modelcontextprotocol/ext-apps": "git+https://github.com/modelcontextprotocol/ext-apps.git",
+    "@modelcontextprotocol/ext-apps": "../..",
-    "@modelcontextprotocol/sdk": "^1.20.1",
+    "@modelcontextprotocol/sdk": "^1.22.0",
     "react": "^19.2.0",
     "react-dom": "^19.2.0",
     "zod": "^3.25.0"
@@ -23,6 +21,7 @@
     "@types/react": "^19.2.2",
     "@types/react-dom": "^19.2.2",
     "@vitejs/plugin-react": "^4.3.4",
+    "concurrently": "^9.2.1",
     "cors": "^2.8.5",
     "express": "^5.1.0",
     "typescript": "^5.7.2",

examples/simple-server/server.ts

@@ -36,94 +36,122 @@ const getServer = async () => {
   );
 
   // Load HTML for both UIs
-  const [vanillaHtml, reactHtml] = await Promise.all([
+  const [rawHtml, vanillaHtml, reactHtml] = await Promise.all([
+    loadHtml("ui-raw"),
     loadHtml("ui-vanilla"),
     loadHtml("ui-react"),
   ]);
 
-  // --- Vanilla UI Resource & Tool ---
+  const registerResource = (resource: Resource, htmlContent: string) => {
-  const vanillaResource: Resource = {
+    server.registerResource(
-    name: "ui-vanilla-template",
+      resource.name,
-    uri: "ui://vanilla",
+      resource.uri,
-    title: "Vanilla UI Template",
+      resource,
-    description: "A simple vanilla JS UI",
+      async (): Promise<ReadResourceResult> => ({
-    mimeType: "text/html+mcp",
+        contents: [
+          {
+            uri: resource.uri,
+            mimeType: resource.mimeType,
+            text: htmlContent,
+          },
+        ],
+      }),
+    );
+    return resource;
   };
 
-  server.registerResource(
+  {
-    vanillaResource.name,
+    const rawResource = registerResource(
-    vanillaResource.uri,
+      {
-    vanillaResource,
+        name: "ui-raw-template",
-    async (): Promise<ReadResourceResult> => ({
+        uri: "ui://raw",
-      contents: [
+        title: "Raw UI Template",
-        {
+        description: "A simple raw HTML UI",
-          uri: vanillaResource.uri,
+        mimeType: "text/html+mcp",
-          mimeType: vanillaResource.mimeType,
+      },
-          text: vanillaHtml,
+      rawHtml,
+    );
+
+    server.registerTool(
+      "create-ui-raw",
+      {
+        title: "Raw UI",
+        description: "A tool that returns a raw HTML UI (no Apps SDK runtime)",
+        inputSchema: {
+          message: z.string().describe("Message to display"),
         },
-      ],
+        _meta: {
-    }),
+          "ui/resourceUri": rawResource.uri,
-  );
-
-  server.registerTool(
-    "create-ui-vanilla",
-    {
-      title: "Vanilla UI",
-      description: "A tool that returns a simple vanilla JS UI",
-      inputSchema: {
-        message: z.string().describe("Message to display"),
-      },
-      _meta: {
-        "ui/resourceUri": vanillaResource.uri,
-      },
-    },
-    async ({ message }): Promise<CallToolResult> => ({
-      content: [{ type: "text", text: JSON.stringify({ message }) }],
-      structuredContent: { message },
-    }),
-  );
-
-  // --- React UI Resource & Tool ---
-  const reactResource: Resource = {
-    name: "ui-react-template",
-    uri: "ui://react",
-    title: "React UI Template",
-    description: "A React-based UI",
-    mimeType: "text/html+mcp",
-  };
-
-  server.registerResource(
-    reactResource.name,
-    reactResource.uri,
-    reactResource,
-    async (): Promise<ReadResourceResult> => ({
-      contents: [
-        {
-          uri: reactResource.uri,
-          mimeType: reactResource.mimeType,
-          text: reactHtml,
         },
-      ],
+      },
-    }),
+      async ({ message }): Promise<CallToolResult> => ({
-  );
+        content: [{ type: "text", text: JSON.stringify({ message }) }],
+        structuredContent: { message },
+      }),
+    );
+  }
 
-  server.registerTool(
+  {
-    "create-ui-react",
+    const vanillaResource = registerResource(
-    {
+      {
-      title: "React UI",
+        name: "ui-vanilla-template",
-      description: "A tool that returns a React-based UI",
+        uri: "ui://vanilla",
-      inputSchema: {
+        title: "Vanilla UI Template",
-        message: z.string().describe("Message to display"),
+        description: "A simple vanilla JS UI",
+        mimeType: "text/html+mcp",
       },
-      _meta: {
+      vanillaHtml,
-        "ui/resourceUri": reactResource.uri,
+    );
+
+    server.registerTool(
+      "create-ui-vanilla",
+      {
+        title: "Vanilla UI",
+        description: "A tool that returns a vanilla TS + Apps SDK UI",
+        inputSchema: {
+          message: z.string().describe("Message to display"),
+        },
+        _meta: {
+          "ui/resourceUri": vanillaResource.uri,
+        },
       },
-    },
+      async ({ message }): Promise<CallToolResult> => ({
-    async ({ message }): Promise<CallToolResult> => ({
+        content: [{ type: "text", text: JSON.stringify({ message }) }],
-      content: [{ type: "text", text: JSON.stringify({ message }) }],
+        structuredContent: { message },
-      structuredContent: { message },
+      }),
-    }),
+    );
-  );
+  }
+
+  {
+    const reactResource = registerResource(
+      {
+        name: "ui-react-template",
+        uri: "ui://react",
+        title: "React UI Template",
+        description: "A React-based UI",
+        mimeType: "text/html+mcp",
+      },
+      reactHtml,
+    );
+
+    server.registerTool(
+      "create-ui-react",
+      {
+        title: "React UI",
+        description: "A tool that returns a React-based UI",
+        inputSchema: {
+          message: z.string().describe("Message to display"),
+        },
+        _meta: {
+          "ui/resourceUri": reactResource.uri,
+        },
+      },
+      async ({ message }): Promise<CallToolResult> => ({
+        content: [{ type: "text", text: JSON.stringify({ message }) }],
+        structuredContent: { message },
+      }),
+    );
+  }
 
   // --- Common tool: get-weather ---
   server.registerTool(
@@ -252,7 +280,6 @@ app.delete("/mcp", async (req: Request, res: Response) => {
 
 app.listen(MCP_PORT, () => {
   console.log(`MCP Server listening on http://localhost:${MCP_PORT}/mcp`);
-  console.log(`  Tools: create-ui-vanilla, create-ui-react, get-weather`);
 });
 
 process.on("SIGINT", async () => {

examples/simple-server/src/ui-raw.ts

@@ -0,0 +1,243 @@
+/**
+ * @file App that does NOT depend on Apps SDK runtime.
+ *
+ * The Raw UI example has no runtime dependency to the Apps SDK
+ * but still imports its types for static type safety.
+ * Types can be just stripped, e.g. w/ the command line:
+ *
+ * <code>
+ * npx esbuild src/ui-raw.ts --bundle --outfile=dist/ui-raw.js --minify --sourcemap --platform=browser
+ * </code>
+ * 
+ * We implement a barebones JSON-RPC message sender/receiver (see `app` object below),
+ * but without timeouts or runtime type validation of any kind
+ * (for that, use the Apps SDK / see ui-vanilla.ts or ui-react.ts).
+ */
+
+import type {
+  McpUiInitializeRequest,
+  McpUiInitializeResult,
+  McpUiInitializedNotification,
+  McpUiToolResultNotification,
+  McpUiHostContextChangedNotification,
+  McpUiToolInputNotification,
+  McpUiSizeChangeNotification,
+  McpUiMessageRequest,
+  McpUiMessageResult,
+  McpUiOpenLinkRequest,
+  McpUiOpenLinkResult,
+} from "@modelcontextprotocol/ext-apps";
+
+import type {
+  CallToolRequest,
+  CallToolResult,
+  JSONRPCMessage,
+  LoggingMessageNotification,
+} from "@modelcontextprotocol/sdk/types.js";
+
+const app = (() => {
+  type Sendable = { method: string; params: any };
+
+  let nextId = 1;
+
+  return {
+    sendRequest<T extends Sendable, Result>({ method, params }: T) {
+      const id = nextId++;
+      window.parent.postMessage({ jsonrpc: "2.0", id, method, params }, "*");
+      return new Promise<Result>((resolve, reject) => {
+        window.addEventListener("message", function listener(event) {
+          const data: JSONRPCMessage = event.data;
+          if (event.data?.id === id) {
+            window.removeEventListener("message", listener);
+            if (event.data?.result) {
+              resolve(event.data.result as Result);
+            } else if (event.data?.error) {
+              reject(new Error(event.data.error));
+            }
+          } else {
+            reject(new Error(`Unsupported message: ${JSON.stringify(data)}`));
+          }
+        });
+      });
+    },
+    sendNotification<T extends Sendable>({ method, params }: T) {
+      window.parent.postMessage({ jsonrpc: "2.0", method, params }, "*");
+    },
+    onNotification<T extends Sendable>(
+      method: T["method"],
+      handler: (params: T["params"]) => void,
+    ) {
+      window.addEventListener("message", function listener(event) {
+        if (event.data?.method === method) {
+          handler(event.data.params);
+        }
+      });
+    },
+  };
+})();
+
+window.addEventListener("load", async () => {
+  const root = document.getElementById("root")!;
+  const appendText = (textContent: string, opts = {}) => {
+    root.appendChild(
+      Object.assign(document.createElement("div"), {
+        textContent,
+        ...opts,
+      }),
+    );
+  };
+  const appendError = (error: unknown) =>
+    appendText(
+      `Error: ${error instanceof Error ? error.message : String(error)}`,
+      { style: "color: red;" },
+    );
+
+  app.onNotification<McpUiToolInputNotification>(
+    "ui/notifications/tool-input",
+    async (params) => {
+      appendText(`Tool call input: ${JSON.stringify(params)}`);
+    },
+  );
+  app.onNotification<McpUiToolResultNotification>(
+    "ui/notifications/tool-result",
+    async (params) => {
+      appendText(`Tool call result: ${JSON.stringify(params)}`);
+    },
+  );
+  app.onNotification<McpUiHostContextChangedNotification>(
+    "ui/notifications/host-context-changed",
+    async (params) => {
+      appendText(`Host context changed: ${JSON.stringify(params)}`);
+    },
+  );
+
+  const initializeResult = await app.sendRequest<
+    McpUiInitializeRequest,
+    McpUiInitializeResult
+  >({
+    method: "ui/initialize",
+    params: {
+      appCapabilities: {},
+      appInfo: { name: "My UI", version: "1.0.0" },
+      protocolVersion: "2025-06-18",
+    },
+  });
+
+  appendText(`Initialize result: ${JSON.stringify(initializeResult)}`);
+
+  app.sendNotification<McpUiInitializedNotification>({
+    method: "ui/notifications/initialized",
+    params: {},
+  });
+
+  new ResizeObserver(() => {
+    const { body, documentElement: html } = document;
+
+    const bodyStyle = getComputedStyle(body);
+    const htmlStyle = getComputedStyle(html);
+
+    const width = body.scrollWidth;
+    const height =
+      body.scrollHeight +
+      (parseFloat(bodyStyle.borderTop) || 0) +
+      (parseFloat(bodyStyle.borderBottom) || 0) +
+      (parseFloat(htmlStyle.borderTop) || 0) +
+      (parseFloat(htmlStyle.borderBottom) || 0);
+
+    app.sendNotification<McpUiSizeChangeNotification>({
+      method: "ui/notifications/size-change",
+      params: { width, height },
+    });
+  }).observe(document.body);
+
+  root.appendChild(
+    Object.assign(document.createElement("button"), {
+      textContent: "Get Weather (Tool)",
+      onclick: async () => {
+        try {
+          const result = await app.sendRequest<CallToolRequest, CallToolResult>(
+            {
+              method: "tools/call",
+              params: {
+                name: "get-weather",
+                arguments: { location: "Tokyo" },
+              },
+            },
+          );
+
+          appendText(`Weather tool result: ${JSON.stringify(result)}`);
+        } catch (e) {
+          appendError(e);
+        }
+      },
+    }),
+  );
+
+  root.appendChild(
+    Object.assign(document.createElement("button"), {
+      textContent: "Notify Cart Updated",
+      onclick: async () => {
+        app.sendNotification<LoggingMessageNotification>({
+          method: "notifications/message",
+          params: {
+            level: "info",
+            data: "cart-updated",
+          },
+        });
+      },
+    }),
+  );
+
+  root.appendChild(
+    Object.assign(document.createElement("button"), {
+      textContent: "Prompt Weather in Tokyo",
+      onclick: async () => {
+        try {
+          const { isError } = await app.sendRequest<
+            McpUiMessageRequest,
+            McpUiMessageResult
+          >({
+            method: "ui/message",
+            params: {
+              role: "user",
+              content: [
+                {
+                  type: "text",
+                  text: "What is the weather in Tokyo?",
+                },
+              ],
+            },
+          });
+
+          appendText(`Message result: ${isError ? "error" : "success"}`);
+        } catch (e) {
+          appendError(e);
+        }
+      },
+    }),
+  );
+
+  root.appendChild(
+    Object.assign(document.createElement("button"), {
+      textContent: "Open Link to Google",
+      onclick: async () => {
+        try {
+          const { isError } = await app.sendRequest<
+            McpUiOpenLinkRequest,
+            McpUiOpenLinkResult
+          >({
+            method: "ui/open-link",
+            params: {
+              url: "https://www.google.com",
+            },
+          });
+          appendText(`Link result: ${isError ? "error" : "success"}`);
+        } catch (e) {
+          appendError(e);
+        }
+      },
+    }),
+  );
+
+  console.log("Initialized with host info:", initializeResult.hostInfo);
+});

examples/simple-server/src/ui-react.tsx

@@ -1,3 +1,6 @@
+/**
+ * @file App that demonstrates a few features using React + the Apps SDK.
+ */
 import { useState, useCallback } from "react";
 import { createRoot } from "react-dom/client";
 import {
@@ -13,8 +16,8 @@ import type {
 const APP_INFO: Implementation = {
   name: "MCP UI React Example Client",
   version: "1.0.0",
-  protocolVersion: "2025-06-18",
 };
+
 export function McpClientApp() {
   const [toolResults, setToolResults] = useState<CallToolResult[]>([]);
   const [messages, setMessages] = useState<string[]>([]);

examples/simple-server/src/ui-vanilla.ts

@@ -1,9 +1,18 @@
+/**
+ * @file Demonstrate a few Apps SDK features.
+ *
+ * The vanilla (no React) UI uses the Apps SDK.
+ *
+ * The Apps SDK offers advantages over the Raw UI example,
+ * such as ability to set timeouts, strong runtime type validation
+ * and simpler methods for each request/response interaction.
+ */
 import {
   App,
   PostMessageTransport,
   McpUiToolInputNotificationSchema,
-  McpUiSizeChangeNotificationSchema,
   McpUiToolResultNotificationSchema,
+  McpUiHostContextChangedNotificationSchema,
 } from "@modelcontextprotocol/ext-apps";
 
 window.addEventListener("load", async () => {
@@ -27,6 +36,14 @@ window.addEventListener("load", async () => {
     version: "1.0.0",
   });
 
+  app.setNotificationHandler(
+    McpUiToolInputNotificationSchema,
+    async ({ params }) => {
+      appendText(
+        `Tool call input received: ${JSON.stringify(params.arguments)}`,
+      );
+    },
+  );
   app.setNotificationHandler(
     McpUiToolResultNotificationSchema,
     async ({ params: { content, structuredContent, isError } }) => {
@@ -36,19 +53,9 @@ window.addEventListener("load", async () => {
     },
   );
   app.setNotificationHandler(
-    McpUiSizeChangeNotificationSchema,
+    McpUiHostContextChangedNotificationSchema,
-    async ({ params: { width, height } }) => {
+    async (params) => {
-      appendText(
+      appendText(`Host context changed: ${JSON.stringify(params)}`);
-        `Size change notification received: width=${width}, height=${height}`,
-      );
-    },
-  );
-  app.setNotificationHandler(
-    McpUiToolInputNotificationSchema,
-    async ({ params }) => {
-      appendText(
-        `Tool call input received: ${JSON.stringify(params.arguments)}`,
-      );
     },
   );
 

examples/simple-server/ui-raw.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>MCP UI Client (Raw)</title>
+</head>
+<body>
+    <div id="root"></div>
+    <script type="module" src="/src/ui-raw.ts"></script>
+</body>
+</html>

examples/simple-server/vite.config.ts

@@ -4,13 +4,13 @@ import { viteSingleFile } from "vite-plugin-singlefile";
 import { resolve } from "path";
 
 // Get the entry from environment variable, default to ui-react
-const entry = process.env.VITE_ENTRY || "ui-react";
+const uiPath = process.env.UI;
 
 export default defineConfig({
   plugins: [react(), viteSingleFile()],
   build: {
     rollupOptions: {
-      input: resolve(__dirname, `${entry}.html`),
+      input: uiPath,
     },
     outDir: `dist`,
     emptyOutDir: false,

package.json

@@ -7,16 +7,16 @@
   "main": "./dist/src/app.js",
   "exports": {
     ".": {
-      "default": "./dist/src/app.js",
+      "types": "./dist/src/app.d.ts",
-      "types": "./dist/src/app.d.ts"
+      "default": "./dist/src/app.js"
     },
     "./react": {
-      "default": "./dist/src/react/index.js",
+      "types": "./dist/src/react/index.d.ts",
-      "types": "./dist/src/react/index.d.ts"
+      "default": "./dist/src/react/index.js"
     },
     "./app-bridge": {
-      "default": "./dist/src/app-bridge.js",
+      "types": "./dist/src/app-bridge.d.ts",
-      "types": "./dist/src/app-bridge.d.ts"
+      "default": "./dist/src/app-bridge.js"
     }
   },
   "files": [
@@ -44,7 +44,7 @@
     "prettier": "^3.6.2"
   },
   "dependencies": {
-    "@modelcontextprotocol/sdk": "^1.20.1",
+    "@modelcontextprotocol/sdk": "^1.22.0",
     "bun": "^1.3.2",
     "react": "^19.2.0",
     "react-dom": "^19.2.0",

src/react/index.tsx

@@ -1,2 +1,2 @@
 export * from "./useApp";
-export * from "./useAutoResize";
+export * from "./useAutoResize";