There are around 760+ sessions/tutorials/events at GDC 2019, finding the sessions that a tools developer would be interested in takes time. Below you will find a list of sessions that can become the base for your tools developer GDC 2019 experience, whether you plan on attending or you will be viewing post-factum.
GDC 2018, Tools Tutorial Day, Ludovic Chabant, Senior Software Engineer @ Electronic Arts Vancouver shared the know-how of the Frostbite engine team when it comes to designing the game's data.
There are around 650+ sessions at this year's GDC, and it isn't easy to find sessions that you as a tools developer might enjoy. I have tried to find and collect most of the talks that a tools developer would be interested in attending or watching after the fact.