You need a 1/4” notched trowel and sharp scissors and carpet knife for certain. You may need to keep switching out blades to keep a sharp edge. Depending on your installation, you might need sand paper and a screwdriver too. It also is important to have a carpet roller, the back of a shop broom, or a small sanded 2×6 to push over the carpet to force the glue up into the rows of knots on the back of the carpeting.