diff --git a/python/packages/autogen-agentchat/src/autogen_agentchat/agents/_base_chat_agent.py b/python/packages/autogen-agentchat/src/autogen_agentchat/agents/_base_chat_agent.py
index b4e58546c05a..b17bf18c309e 100644
--- a/python/packages/autogen-agentchat/src/autogen_agentchat/agents/_base_chat_agent.py
+++ b/python/packages/autogen-agentchat/src/autogen_agentchat/agents/_base_chat_agent.py
@@ -1,5 +1,10 @@
 from abc import ABC, abstractmethod
-from typing import Any, AsyncGenerator, List, Mapping, Sequence
+from typing import Any, AsyncGenerator, List, Mapping, Sequence, get_args, get_origin
+
+try:
+    from typing import Annotated
+except ImportError:
+    from typing_extensions import Annotated
 
 from autogen_core import CancellationToken
 
@@ -79,12 +84,12 @@ async def run(
             output_messages.append(text_msg)
         elif isinstance(task, list):
             for msg in task:
-                if isinstance(msg, (TextMessage, MultiModalMessage, StopMessage, HandoffMessage)):
+                if get_origin(ChatMessage) is Annotated and msg.__class__ in get_args(ChatMessage)[0].__args__:
                     input_messages.append(msg)
                     output_messages.append(msg)
                 else:
                     raise ValueError(f"Invalid message type in list: {type(msg)}")
-        elif isinstance(task, (TextMessage, MultiModalMessage, StopMessage, HandoffMessage)):
+        elif get_origin(ChatMessage) is Annotated and task.__class__ in get_args(ChatMessage)[0].__args__:
             input_messages.append(task)
             output_messages.append(task)
         else:
@@ -116,13 +121,13 @@ async def run_stream(
             yield text_msg
         elif isinstance(task, list):
             for msg in task:
-                if isinstance(msg, (TextMessage, MultiModalMessage, StopMessage, HandoffMessage)):
+                if get_origin(ChatMessage) is Annotated and msg.__class__ in get_args(ChatMessage)[0].__args__:
                     input_messages.append(msg)
                     output_messages.append(msg)
                     yield msg
                 else:
                     raise ValueError(f"Invalid message type in list: {type(msg)}")
-        elif isinstance(task, (TextMessage, MultiModalMessage, StopMessage, HandoffMessage)):
+        elif get_origin(ChatMessage) is Annotated and task.__class__ in get_args(ChatMessage)[0].__args__:
             input_messages.append(task)
             output_messages.append(task)
             yield task
diff --git a/python/packages/autogen-agentchat/src/autogen_agentchat/teams/_group_chat/_base_group_chat.py b/python/packages/autogen-agentchat/src/autogen_agentchat/teams/_group_chat/_base_group_chat.py
index 3856ea7fcf0a..2de743c6297d 100644
--- a/python/packages/autogen-agentchat/src/autogen_agentchat/teams/_group_chat/_base_group_chat.py
+++ b/python/packages/autogen-agentchat/src/autogen_agentchat/teams/_group_chat/_base_group_chat.py
@@ -2,7 +2,12 @@
 import logging
 import uuid
 from abc import ABC, abstractmethod
-from typing import Any, AsyncGenerator, Callable, List, Mapping
+from typing import Any, AsyncGenerator, Callable, List, Mapping, get_args, get_origin
+
+try:
+    from typing import Annotated
+except ImportError:
+    from typing_extensions import Annotated
 
 from autogen_core import (
     AgentId,
@@ -368,12 +373,15 @@ async def main() -> None:
             pass
         elif isinstance(task, str):
             first_chat_message = TextMessage(content=task, source="user")
-        elif isinstance(task, (TextMessage, MultiModalMessage, StopMessage, HandoffMessage)):
+        elif get_origin(ChatMessage) is Annotated and task.__class__ in get_args(ChatMessage)[0].__args__:
             first_chat_message = task
         elif isinstance(task, list):
             if not task:
                 raise ValueError("Task list cannot be empty")
-            if not all(isinstance(msg, (TextMessage, MultiModalMessage, StopMessage, HandoffMessage)) for msg in task):
+            if not all(
+                get_origin(ChatMessage) is Annotated and msg.__class__ in get_args(ChatMessage)[0].__args__
+                for msg in task
+            ):
                 raise ValueError("All messages in task list must be valid ChatMessage types")
             first_chat_message = task[0]
             # Queue remaining messages for processing