"Not up to snuff" refers to something that is not satisfactory or up to standards. Antonyms for this phrase may include "impressive," "excellent," "outstanding," or "remarkable." These words indicate that the object, person or situation meets or even exceeds expectations. Other antonyms may include "adequate," "acceptable," or "decent." These suggest that while the item may not be exceptional, it is still sufficient and meets the requirements. Overall, using antonyms for "not up to snuff" can help to highlight the positive qualities of something and provide a more optimistic outlook.