Whenever you divide a material into sections - whether you're felling a tree with an axe, piercing metal with a saw, or cutting a slice of birthday cake, the amount of material that is wasted by the thickness of the tool is called the 'kerf'. This is also the term I use for the amount of clay that is dragged away from a fresh slab of metal clay when using a pointy tool to cut a shape. If the tool is thick, the kerf is wide. If one uses a thinner stylus or 'needle' tool, the kerf is narrower and the piece of fresh clay tends to retain it's shape better. I'm sure you've noticed that the clay is sometimes pulled out of alignment as a 'pin tool' drags a path through the clay. A thinner tool won't do that. A friend of mine uses an ultra thin beading needle that makes a practically unnoticeable cut, but I find something THAT thin to be too bendy and unwieldy. Especially if I've already had my morning cup of coffee.
I use an actual dressmaker's pin when using a template to cut a shape in clay, you know - the ones with the pretty pearl on top? I suppose I could set it into a thin wooden dowel, or make a polymer clay or thermoplastic handle for it - but I like the pearls and have a wire shelf in my studio that contains the pins perfectly.
So the next time you're reaching for a tool to remove a tiny bit of clay from a big slab, think about how much you can afford to 'lose' to the kerf. That might encourage you to reach for a tool with a narrower tip.