Add tool result _meta in tool response and access in the ui

examples/quickstart/mcp-app.html

@@ -8,6 +8,9 @@
     <p>
       <strong>Server Time:</strong> <code id="server-time">Loading...</code>
     </p>
+    <p>
+      <strong>Tool Meta Source:</strong> <code id="tool-meta-source">[none]</code>
+    </p>
     <button id="get-time-btn">Get Server Time</button>
     <script type="module" src="/src/mcp-app.ts"></script>
   </body>

examples/quickstart/server.ts

@@ -35,7 +35,14 @@ export function createServer(): McpServer {
     },
     async () => {
       const time = new Date().toISOString();
-      return { content: [{ type: "text", text: time }] };
+      return {
+        content: [{ type: "text", text: time }],
+        _meta: {
+          timestamp: time,
+          source: "quickstart-server",
+          debugToken: "quickstart-meta-debug",
+        },
+      };
     },
   );
 

examples/quickstart/src/mcp-app.ts

@@ -2,24 +2,34 @@ import { App } from "@modelcontextprotocol/ext-apps";
 
 // Get element references
 const serverTimeEl = document.getElementById("server-time")!;
+const toolMetaSourceEl = document.getElementById("tool-meta-source")!;
 const getTimeBtn = document.getElementById("get-time-btn")!;
 
 // Create app instance
 const app = new App({ name: "Get Time App", version: "1.0.0" });
 
+function extractMetaSource(result: unknown): string {
+  const meta = (result as { _meta?: { source?: unknown } })._meta;
+  return typeof meta?.source === "string" ? meta.source : "[missing]";
+}
+
 // Handle tool results from the server. Set before `app.connect()` to avoid
 // missing the initial tool result.
 app.ontoolresult = (result) => {
+  console.info("tool-result _meta:", (result as { _meta?: unknown })._meta);
   const time = result.content?.find((c) => c.type === "text")?.text;
   serverTimeEl.textContent = time ?? "[ERROR]";
+  toolMetaSourceEl.textContent = extractMetaSource(result);
 };
 
 // Wire up button click
 getTimeBtn.addEventListener("click", async () => {
   // `app.callServerTool()` lets the UI request fresh data from the server
   const result = await app.callServerTool({ name: "get-time", arguments: {} });
+  console.info("callServerTool _meta:", (result as { _meta?: unknown })._meta);
   const time = result.content?.find((c) => c.type === "text")?.text;
   serverTimeEl.textContent = time ?? "[ERROR]";
+  toolMetaSourceEl.textContent = extractMetaSource(result);
 });
 
 // Connect to host