Why is this the answer?

The answer is scissors because this wonderful riddle is a secret code describing exactly what a pair of scissors is and what it does. Let us look at each part of the riddle to see how it matches our answer. The first line says, "I open wide and tight I shut." Think about using scissors to cut out a big shape for an art project. You open the two metal blades far apart, like two arms stretching wide, and then you squeeze your fingers to shut them tight to slice through the paper. Scissors make that opening and closing motion over and over again to do their job. It is like they are clapping their metal hands together, but instead of making a sound, they cut! Next, the riddle mentions, "Sharp am I and paper-cut fingers too, so do take care." This is the most important clue! Scissors must be sharp to cut through strong things like cardstock or fabric. That is their special power. But the riddle also gives a warning: a sharp tool must be used carefully. If you are rushing, or if you hold the paper in a funny way, those sharp edges might accidentally catch your finger. The phrase "paper-cut fingers too" is a fun trick, reminding us to keep our fingers safe and away from the moving blades. The last part sums it all up: "I'm good and bad, so best beware." How can one tool be both good and bad? Scissors are good because they are one of the most helpful tools you can have. They cut ribbon for presents, trim edges for homework, and turn a plain piece of paper into a cool design. They are bad, not because they are evil, but because they have the potential to hurt you if you forget the safety rules. You always have to be very aware when you are using something so sharp. You must treat them like a professional tool and always point the blades down when carrying them. This riddle is a clever way to remember that you should always handle a pair of sharp scissors with care and respect. Every part of the poem points right to the two sharp, hinged pieces of metal we call scissors.