If you want to pick colors for your UI, you should first design in grayscale, then add color (while preserving the perceived lightness using a reasonable color model like CIELAB or CIECAM02 or ...).

This tool is likely to create confusion and yield poor results in the hands of someone who isn’t already an expert (either through studying human vision or long practice as a visual artist), because the numerical values sound important and technical, but in the HSL color model are actually rather arbitrary and unrelated to human vision.