diff --git a/frontend/src/components/ChatPanel.tsx b/frontend/src/components/ChatPanel.tsx
index 53d7a98..d44d597 100644
--- a/frontend/src/components/ChatPanel.tsx
+++ b/frontend/src/components/ChatPanel.tsx
@@ -3,6 +3,7 @@ import type { KeyboardEvent } from 'react'
 import ReactMarkdown from 'react-markdown'
 import { IconSend } from '@tabler/icons-react'
 import { ToolCallCard } from './ToolCallCard'
+import { MCPAppRenderer } from './MCPAppRenderer'
 import type { ChatMessage } from '../hooks/useChat'
 
 interface ChatPanelProps {
@@ -61,9 +62,19 @@ export function ChatPanel({ messages, isStreaming, onSend, sessionId }: ChatPane
             {message.role === 'assistant' ? (
               <div>
                 <ReactMarkdown>{message.content}</ReactMarkdown>
-                {message.toolCalls?.map(tc => (
-                  <ToolCallCard key={tc.id} toolCall={tc} />
-                ))}
+                {message.toolCalls?.map(tc =>
+                  tc._meta?.ui?.resourceUri ? (
+                    <MCPAppRenderer
+                      key={tc.id}
+                      resourceUri={tc._meta.ui.resourceUri}
+                      data={tc.structuredContent ?? {}}
+                      csp={tc._meta.ui.csp}
+                      onSendMessage={(content) => onSend(content)}
+                    />
+                  ) : (
+                    <ToolCallCard key={tc.id} toolCall={tc} />
+                  )
+                )}
               </div>
             ) : (
               <div>{message.content}</div>
diff --git a/frontend/src/test/ChatPanel.test.tsx b/frontend/src/test/ChatPanel.test.tsx
index 4b434a1..7f23bc1 100644
--- a/frontend/src/test/ChatPanel.test.tsx
+++ b/frontend/src/test/ChatPanel.test.tsx
@@ -14,6 +14,13 @@ vi.mock('react-markdown', () => ({
   default: ({ children }: { children: string }) => <div>{children}</div>,
 }))
 
+// Mock MCPAppRenderer to avoid fetch/iframe in test environment
+vi.mock('../components/MCPAppRenderer', () => ({
+  MCPAppRenderer: ({ resourceUri }: { resourceUri: string }) => (
+    <div data-testid='mcp-app-renderer' data-resource-uri={resourceUri} />
+  ),
+}))
+
 describe('ChatPanel', () => {
   const noop = () => undefined
 
@@ -90,6 +97,72 @@ describe('ChatPanel', () => {
       expect(container.querySelector('.tool-call-card')).toBeTruthy()
     })
 
+    it('renders MCPAppRenderer for tool calls with _meta.ui.resourceUri', () => {
+      const messages: ChatMessage[] = [
+        {
+          id: '1',
+          role: 'assistant',
+          content: 'Running an MCP app',
+          toolCalls: [
+            {
+              id: 'tc-mcp',
+              name: 'mcp_app',
+              args: {},
+              status: 'complete',
+              _meta: { ui: { resourceUri: 'app://chart' } },
+              structuredContent: { value: 42 },
+            },
+          ],
+        },
+      ]
+      render(
+        <ChatPanel messages={messages} isStreaming={false} onSend={noop} sessionId={sessionId} />
+      )
+      expect(screen.getByTestId('mcp-app-renderer')).toBeTruthy()
+    })
+
+    it('does not render ToolCallCard for tool calls with _meta.ui.resourceUri', () => {
+      const messages: ChatMessage[] = [
+        {
+          id: '1',
+          role: 'assistant',
+          content: 'Running an MCP app',
+          toolCalls: [
+            {
+              id: 'tc-mcp',
+              name: 'mcp_app',
+              args: {},
+              status: 'complete',
+              _meta: { ui: { resourceUri: 'app://chart' } },
+              structuredContent: { value: 42 },
+            },
+          ],
+        },
+      ]
+      const { container } = render(
+        <ChatPanel messages={messages} isStreaming={false} onSend={noop} sessionId={sessionId} />
+      )
+      expect(container.querySelector('.tool-call-card')).toBeNull()
+    })
+
+    it('renders ToolCallCard for tool calls without _meta.ui.resourceUri', () => {
+      const messages: ChatMessage[] = [
+        {
+          id: '1',
+          role: 'assistant',
+          content: 'Running a plain tool',
+          toolCalls: [
+            { id: 'tc-plain', name: 'bash', args: {}, status: 'complete' },
+          ],
+        },
+      ]
+      const { container } = render(
+        <ChatPanel messages={messages} isStreaming={false} onSend={noop} sessionId={sessionId} />
+      )
+      expect(container.querySelector('.tool-call-card')).toBeTruthy()
+      expect(screen.queryByTestId('mcp-app-renderer')).toBeNull()
+    })
+
     it('shows Researching... when isStreaming and messages exist', () => {
       const messages: ChatMessage[] = [
         { id: '1', role: 'user', content: 'Question' },