Improve tool use order

custom_tools.py

@@ -141,10 +141,11 @@ def wiki_search(query: str) -> str:
 def sum_excel_cols(file_name: str, column_names: List[str]) -> float:
     """
     Sum the values of specified columns in a pandas DataFrame read from an Excel file.
+    This tool should NEVER be called if you're not sure which columns to sum. If you need to retrieve column names, you must do so from the output of the read_file_content tool.
 
     Args:
         file_name (str): The path to the Excel file.
-        column_names (List[str]): A list of column names to sum. The column names need to exist and should be extracted from the input of the read_file_content tool
+        column_names (List[str]): A list of column names to sum. Column names must first be retrieved from the output of the read_file_content tool.
 
     Returns:
         float: The sum of the specified columns.
@@ -221,12 +222,12 @@ def read_file_content(file_name: str) -> str:
         str: The content of the file, or a detailed error message.
     """
     download_state = download_file(file_name)
-    if download_state == f"Success downloading {file_name}":
-        file_content = read_file(file_name)
-    
-    return file_content
-
 
+    if download_state.startswith("Success") or "already exists" in download_state:
+        return read_file(file_name)
+    else:
+        return download_state  # Return the error message from downloading
+    
 @tool 
 def analyse_youtube_video(url: str, video_question: str):
     """