diff --git a/letta/schemas/letta_request.py b/letta/schemas/letta_request.py
index 123d817c..f1f8f450 100644
--- a/letta/schemas/letta_request.py
+++ b/letta/schemas/letta_request.py
@@ -11,6 +11,10 @@ class LettaRequest(BaseModel):
 
     # Flags to support the use of AssistantMessage message types
 
+    use_assistant_message: bool = Field(
+        default=True,
+        description="Whether the server should parse specific tool call arguments (default `send_message`) as `AssistantMessage` objects.",
+    )
     assistant_message_tool_name: str = Field(
         default=DEFAULT_MESSAGE_TOOL,
         description="The name of the designated message tool.",
diff --git a/letta/server/rest_api/routers/v1/agents.py b/letta/server/rest_api/routers/v1/agents.py
index 96d29777..5ab19348 100644
--- a/letta/server/rest_api/routers/v1/agents.py
+++ b/letta/server/rest_api/routers/v1/agents.py
@@ -493,6 +493,7 @@ async def send_message(
         stream_steps=False,
         stream_tokens=False,
         # Support for AssistantMessage
+        use_assistant_message=request.use_assistant_message,
         assistant_message_tool_name=request.assistant_message_tool_name,
         assistant_message_tool_kwarg=request.assistant_message_tool_kwarg,
     )
@@ -638,6 +639,7 @@ async def send_message_to_agent(
     chat_completion_mode: bool = False,
     timestamp: Optional[datetime] = None,
     # Support for AssistantMessage
+    use_assistant_message: bool = True,
     assistant_message_tool_name: str = DEFAULT_MESSAGE_TOOL,
     assistant_message_tool_kwarg: str = DEFAULT_MESSAGE_TOOL_KWARG,
 ) -> Union[StreamingResponse, LettaResponse]:
@@ -668,7 +670,7 @@ async def send_message_to_agent(
             stream_tokens = False
 
         # Create a new interface per request
-        letta_agent.interface = StreamingServerInterface()
+        letta_agent.interface = StreamingServerInterface(use_assistant_message)
         streaming_interface = letta_agent.interface
         if not isinstance(streaming_interface, StreamingServerInterface):
             raise ValueError(f"Agent has wrong type of interface: {type(streaming_interface)}")