fix: tool return message packing in stream (#2586)

letta/schemas/message.py

@@ -383,6 +383,7 @@ class Message(BaseMessage):
 
             try:
                 function_return = parse_json(text_content)
+                text_content = str(function_return.get("message", text_content))
                 status = function_return["status"]
                 if status == "OK":
                     status_enum = "success"

tests/test_server.py

@@ -696,7 +696,7 @@ def _test_get_messages_letta_format(
 
             elif message.role == MessageRole.tool:
                 assert isinstance(letta_message, ToolReturnMessage)
-                assert message.content[0].text == letta_message.tool_return
+                assert str(json.loads(message.content[0].text)["message"]) == letta_message.tool_return
                 letta_message_index += 1
 
             else: