The must have tools you need when fly fishing. First you need a good pair of line cutters (nippers) Try to find something in a fluro colour and non reflective, it is advisable to have them attached to a lanyard on your vest. You will also need a quality set of forceps, I like the sissor forceps as they have the scissor that is usefull for trimming flies. Most scissor forceps have a screwdriver head in the handle that is hand for streamside reel repairs. so three tools in one. Some sort of tippet organisr that can be attached to your vest saves you rabbiting through your vest looking for the right tippet. You will also need to carry floatant strike indicators and spare leaders. The choice of what you can carry is endless try to keep it to a minimum, I like to go through my vest at the beginning of each season to reveue wether I can iliminate some things to cut down on weight. It's suprising how quickly the weight in your vest increases.