The layer tools are similar to layers in Photoshop and Substance Painter. They will build from the bottom-up in the layer stack. The tools are built-in, and while the API will eventually be released for expansion, at this time Project Alchemist remains in Alpha (Beta soon) and does not have expansion capabilities per user yet.
Images Import - Allows you to import images.
Bitmap to Material - Takes an existing photograph to create a material
Equalizer - Adjusts contrast to reduce naturally occurring seams resulting from heavy shadows in the original image.
Tiling - Crops and supports setting tiling
Clone Patch - Healing brush in Photoshop
Delighter - Removes shadows to create an albedo map.