add constant for error message prefix

letta/agent.py

@@ -10,6 +10,7 @@
 from letta.constants import (
     BASE_TOOLS,
     CLI_WARNING_PREFIX,
+    ERROR_MESSAGE_PREFIX,
     FIRST_MESSAGE_ATTEMPTS,
     FUNC_FAILED_HEARTBEAT_MESSAGE,
     IN_CONTEXT_MEMORY_KEYWORD,
@@ -863,7 +864,7 @@ def _handle_ai_response(
                 return messages, False, True  # force a heartbeat to allow agent to handle error
 
             # Step 4: check if function response is an error
-            if function_response_string.startswith("Error"):
+            if function_response_string.startswith(ERROR_MESSAGE_PREFIX):
                 function_response = package_function_response(False, function_response_string)
                 # TODO: truncate error message somehow
                 messages.append(

letta/constants.py

@@ -69,6 +69,8 @@
 
 CLI_WARNING_PREFIX = "Warning: "
 
+ERROR_MESSAGE_PREFIX = "Error"
+
 NON_USER_MSG_PREFIX = "[This is an automated system message hidden from the user] "
 
 # Constants to do with summarization / conversation length window

letta/utils.py

@@ -28,6 +28,7 @@
     CLI_WARNING_PREFIX,
     CORE_MEMORY_HUMAN_CHAR_LIMIT,
     CORE_MEMORY_PERSONA_CHAR_LIMIT,
+    ERROR_MESSAGE_PREFIX,
     LETTA_DIR,
     MAX_FILENAME_LENGTH,
     TOOL_CALL_ID_MAX_LEN,
@@ -1122,7 +1123,7 @@ def sanitize_filename(filename: str) -> str:
 def get_friendly_error_msg(function_name: str, exception_name: str, exception_message: str):
     from letta.constants import MAX_ERROR_MESSAGE_CHAR_LIMIT
 
-    error_msg = f"Error executing function {function_name}: {exception_name}: {exception_message}"
+    error_msg = f"{ERROR_MESSAGE_PREFIX} executing function {function_name}: {exception_name}: {exception_message}"
     if len(error_msg) > MAX_ERROR_MESSAGE_CHAR_LIMIT:
         error_msg = error_msg[:MAX_ERROR_MESSAGE_CHAR_LIMIT]
     return error_msg