ShaderTool system requirements state that you will need at least 4 GB of RAM. The cheapest graphics card you can play it on is an AMD Radeon HD 6250. To play ShaderTool you will need a minimum CPU equivalent to an Intel Core i3-530. In terms of game file size, you will need at least 50 MB of free disk space available.
ShaderTool will run on PC system with 7, 8, 8.1 32-bit or 64-bit and upwards.