diff --git a/autogen/agentchat/assistant_agent.py b/autogen/agentchat/assistant_agent.py
index 4a0200fb6720..b39b5f75f80e 100644
--- a/autogen/agentchat/assistant_agent.py
+++ b/autogen/agentchat/assistant_agent.py
@@ -1,5 +1,5 @@
 from .conversable_agent import ConversableAgent
-from typing import Callable, Dict, Optional, Union
+from typing import Callable, Dict, Literal, Optional, Union
 
 
 class AssistantAgent(ConversableAgent):
@@ -30,11 +30,11 @@ def __init__(
         self,
         name: str,
         system_message: Optional[str] = DEFAULT_SYSTEM_MESSAGE,
-        llm_config: Optional[Union[Dict, bool]] = None,
+        llm_config: Optional[Union[Dict, Literal[False]]] = None,
         is_termination_msg: Optional[Callable[[Dict], bool]] = None,
         max_consecutive_auto_reply: Optional[int] = None,
         human_input_mode: Optional[str] = "NEVER",
-        code_execution_config: Optional[Union[Dict, bool]] = False,
+        code_execution_config: Optional[Union[Dict, Literal[False]]] = False,
         **kwargs,
     ):
         """
diff --git a/autogen/agentchat/conversable_agent.py b/autogen/agentchat/conversable_agent.py
index eec164ce822b..ab222662e1ee 100644
--- a/autogen/agentchat/conversable_agent.py
+++ b/autogen/agentchat/conversable_agent.py
@@ -3,7 +3,7 @@
 import copy
 import json
 import logging
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
+from typing import Any, Callable, Dict, List, Literal, Optional, Tuple, Type, Union
 from autogen import OpenAIWrapper
 from .agent import Agent
 from autogen.code_utils import (
@@ -45,6 +45,8 @@ class ConversableAgent(Agent):
     }
     MAX_CONSECUTIVE_AUTO_REPLY = 100  # maximum number of consecutive auto replies (subject to future change)
 
+    llm_config: Union[Dict, Literal[False]]
+
     def __init__(
         self,
         name: str,
@@ -53,8 +55,8 @@ def __init__(
         max_consecutive_auto_reply: Optional[int] = None,
         human_input_mode: Optional[str] = "TERMINATE",
         function_map: Optional[Dict[str, Callable]] = None,
-        code_execution_config: Optional[Union[Dict, bool]] = None,
-        llm_config: Optional[Union[Dict, bool]] = None,
+        code_execution_config: Optional[Union[Dict, Literal[False]]] = None,
+        llm_config: Optional[Union[Dict, Literal[False]]] = None,
         default_auto_reply: Optional[Union[str, Dict, None]] = "",
     ):
         """
@@ -114,7 +116,9 @@ def __init__(
                 self.llm_config.update(llm_config)
             self.client = OpenAIWrapper(**self.llm_config)
 
-        self._code_execution_config = {} if code_execution_config is None else code_execution_config
+        self._code_execution_config: Union[Dict, Literal[False]] = (
+            {} if code_execution_config is None else code_execution_config
+        )
         self.human_input_mode = human_input_mode
         self._max_consecutive_auto_reply = (
             max_consecutive_auto_reply if max_consecutive_auto_reply is not None else self.MAX_CONSECUTIVE_AUTO_REPLY
@@ -135,7 +139,7 @@ def register_reply(
         self,
         trigger: Union[Type[Agent], str, Agent, Callable[[Agent], bool], List],
         reply_func: Callable,
-        position: Optional[int] = 0,
+        position: int = 0,
         config: Optional[Any] = None,
         reset_config: Optional[Callable] = None,
     ):
@@ -162,7 +166,7 @@ def reply_func(
             messages: Optional[List[Dict]] = None,
             sender: Optional[Agent] = None,
             config: Optional[Any] = None,
-        ) -> Union[str, Dict, None]:
+        ) -> Tuple[bool, Union[str, Dict, None]]:
         ```
             position (int): the position of the reply function in the reply function list.
                 The function registered later will be checked earlier by default.
@@ -221,7 +225,7 @@ def chat_messages(self) -> Dict[Agent, List[Dict]]:
         """A dictionary of conversations from agent to list of messages."""
         return self._oai_messages
 
-    def last_message(self, agent: Optional[Agent] = None) -> Dict:
+    def last_message(self, agent: Optional[Agent] = None) -> Optional[Dict]:
         """The last message exchanged with the agent.
 
         Args:
@@ -304,7 +308,7 @@ def send(
         recipient: Agent,
         request_reply: Optional[bool] = None,
         silent: Optional[bool] = False,
-    ) -> bool:
+    ):
         """Send a message to another agent.
 
         Args:
@@ -353,7 +357,7 @@ async def a_send(
         recipient: Agent,
         request_reply: Optional[bool] = None,
         silent: Optional[bool] = False,
-    ) -> bool:
+    ):
         """(async) Send a message to another agent.
 
         Args:
@@ -399,6 +403,8 @@ async def a_send(
     def _print_received_message(self, message: Union[Dict, str], sender: Agent):
         # print the message received
         print(colored(sender.name, "yellow"), "(to", f"{self.name}):\n", flush=True)
+        message = self._message_to_dict(message)
+
         if message.get("role") == "function":
             func_print = f"***** Response from calling function \"{message['name']}\" *****"
             print(colored(func_print, "green"), flush=True)
@@ -606,7 +612,7 @@ def generate_oai_reply(
         self,
         messages: Optional[List[Dict]] = None,
         sender: Optional[Agent] = None,
-        config: Optional[Any] = None,
+        config: Optional[OpenAIWrapper] = None,
     ) -> Tuple[bool, Union[str, Dict, None]]:
         """Generate a reply using autogen.oai."""
         client = self.client if config is None else config
@@ -625,7 +631,7 @@ def generate_code_execution_reply(
         self,
         messages: Optional[List[Dict]] = None,
         sender: Optional[Agent] = None,
-        config: Optional[Any] = None,
+        config: Optional[Union[Dict, Literal[False]]] = None,
     ):
         """Generate a reply using code execution."""
         code_execution_config = config if config is not None else self._code_execution_config
diff --git a/autogen/agentchat/groupchat.py b/autogen/agentchat/groupchat.py
index 604eb5c209db..e5a66438d0a5 100644
--- a/autogen/agentchat/groupchat.py
+++ b/autogen/agentchat/groupchat.py
@@ -1,9 +1,10 @@
-from dataclasses import dataclass
+import logging
 import sys
+from dataclasses import dataclass
 from typing import Dict, List, Optional, Union
+
 from .agent import Agent
 from .conversable_agent import ConversableAgent
-import logging
 
 logger = logging.getLogger(__name__)
 
diff --git a/autogen/agentchat/user_proxy_agent.py b/autogen/agentchat/user_proxy_agent.py
index d72c2bdceba8..8a218b1fe492 100644
--- a/autogen/agentchat/user_proxy_agent.py
+++ b/autogen/agentchat/user_proxy_agent.py
@@ -1,5 +1,5 @@
 from .conversable_agent import ConversableAgent
-from typing import Callable, Dict, Optional, Union
+from typing import Callable, Dict, Literal, Optional, Union
 
 
 class UserProxyAgent(ConversableAgent):
@@ -22,9 +22,9 @@ def __init__(
         max_consecutive_auto_reply: Optional[int] = None,
         human_input_mode: Optional[str] = "ALWAYS",
         function_map: Optional[Dict[str, Callable]] = None,
-        code_execution_config: Optional[Union[Dict, bool]] = None,
+        code_execution_config: Optional[Union[Dict, Literal[False]]] = None,
         default_auto_reply: Optional[Union[str, Dict, None]] = "",
-        llm_config: Optional[Union[Dict, bool]] = False,
+        llm_config: Optional[Union[Dict, Literal[False]]] = False,
         system_message: Optional[str] = "",
     ):
         """