diff --git a/backend/open_webui/utils/tools.py b/backend/open_webui/utils/tools.py
index a8e507d383..f523b6ea0d 100644
--- a/backend/open_webui/utils/tools.py
+++ b/backend/open_webui/utils/tools.py
@@ -1285,7 +1285,7 @@ def convert_openapi_to_tool_payload(openapi_spec):
                             tool['parameters']['properties'].update(resolved_schema['properties'])
                             if 'required' in resolved_schema:
                                 tool['parameters']['required'] = list(
-                                    set(tool['parameters']['required'] + resolved_schema['required'])
+                                    dict.fromkeys(tool['parameters']['required'] + resolved_schema['required'])
                                 )
                         elif resolved_schema.get('type') == 'array':
                             tool['parameters'] = resolved_schema  # special case for array