Update tools.py

tools.py

@@ -88,8 +88,7 @@ if not os.path.exists(index_path):
                 zip_ref.extractall(".")
             os.remove(zip_path)
     except Exception as e:
-        raise Exception(e)
-                
+        raise Exception(f"failed to download index: {e}")
 try:
     tantivy = TantivySearch(index_path)
     tantivy.validate_index()