A utility model patent application must have drawings. If you are applying for a utility model patent and there are no drawings, the examiner will definitely send you a notice of correction to ask you to complete the drawings. At this time, you need to quickly add pictures, otherwise it will be impossible to authorize you. An invention patent application may also be filed without drawings. However, in order to explain clearly, it is of course better to have pictures. When the examiner asks you to correct the attached drawings, he probably thinks that the written description in your answer is not enough to explain the content of your invention.