The phrase "giving the works" is commonly used to describe a complete or thorough performance, action or treatment. However, there are several antonyms that could be used to convey the opposite meaning. Some of these include "holding back," "half-hearted," "minimal effort," or "negligible." These terms suggest a lack of enthusiasm or effort towards the task at hand. Similarly, "incomplete," "partial," or "sketchy" could be used to indicate that only a portion of the job was completed. Overall, these antonyms of "giving the works" convey the idea that a minimal or unsatisfactory level of performance or action was taken, rather than a complete and thorough one.