The word "tosses in" means to include something in a casual or haphazard way. Its antonyms, or opposites, would be words or phrases that suggest a deliberate or planned approach to addition. Some possible antonyms for "tosses in" might include "carefully selects," "thoughtfully includes," "meticulously adds," or "deliberately incorporates." These opposites signify a thoughtful and intentional approach to adding something, whether it be an idea, a detail, or an item. By using these antonyms, one can convey the idea of careful consideration and purposeful decision-making, rather than a haphazard or careless approach.