MCP Apps not supporting Google ADK

[deepakbatham572]

As MCP introduced the mcp apps to use as middleware and render ui as mcp tool ui
Also then copilotkit is introduced the same

refer below
https://docs.copilotkit.ai/whats-new/mcp-apps-support
https://blog.modelcontextprotocol.io/posts/2026-01-26-mcp-apps/

When Google adk will support MCP Apps to render the UI ?

when we are trying to connect the adk agent with copilotkit with agui we are getting python schema validation issue

2026-01-28 14:59:44.676 ERROR [ag_ui_adk.adk_agent] Background execution error: 1 validation error for Schema
$schema
  Extra inputs are not permitted [type=extra_forbidden, input_value='http://json-schema.org/draft-07/schema#', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/extra_forbidden
Traceback (most recent call last):
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/ag_ui_adk/adk_agent.py", line 1627, in _run_adk_in_background
    async for adk_event in runner.run_async(**run_kwargs):
    ...<76 lines>...
                return
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/runners.py", line 562, in run_async
    async for event in agen:
      yield event
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/runners.py", line 550, in _run_with_trace
    async for event in agen:
      yield event
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/runners.py", line 779, in _exec_with_plugin
    async for event in agen:
    ...<64 lines>...
        yield event
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/runners.py", line 539, in execute
    async for event in agen:
      yield event
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/agents/base_agent.py", line 294, in run_async
    async for event in agen:
      yield event
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/agents/llm_agent.py", line 468, in _run_async_impl
    async for event in agen:
    ...<5 lines>...
        should_pause = True
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 382, in run_async
    async for event in agen:
      last_event = event
      yield event
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 401, in _run_one_step_async
    async for event in agen:
      yield event
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 523, in _preprocess_async
    await tool.process_llm_request(
        tool_context=tool_context, llm_request=llm_request
    )
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/tools/base_tool.py", line 129, in process_llm_request
    llm_request.append_tools([self])
    ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/google/adk/models/llm_request.py", line 255, in append_tools
    declaration = tool._get_declaration()
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/ag_ui_adk/client_proxy_tool.py", line 116, in _get_declaration
    parameters=types.Schema.model_validate(parameters)
  File "/Users/deepak.batham/AGUI/testoptimization_with_copilotkit/.venv/lib/python3.13/site-packages/pydantic/main.py", line 716, in model_validate
    return cls.__pydantic_validator__.validate_python(
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        obj,
        ^^^^
    ...<5 lines>...
        by_name=by_name,
        ^^^^^^^^^^^^^^^^
    )
    ^
pydantic_core._pydantic_core.ValidationError: 1 validation error for Schema
$schema
  Extra inputs are not permitted [type=extra_forbidden, input_value='http://json-schema.org/draft-07/schema#', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/extra_forbidden