http://www.ffxicalculator.com/ is THE best tool if you're looking for skill chain. It has the built in skillchain you are looking for and I've used it for years. (of course it has a number of other great features).

Disclaimer: Before anyone even attempt to try it, this is not a "third party tool", as it have absolutely no interaction with the game, therefore, it will not violate the Playonline Terms of Service. This is basically a standalone calculator software for various stuff in game.