When you decompile a model with mdldecompiler it generates a QC file for recompiling, only it adds many useless commands that can cause problems to recompile.
This tool cleans the useless commands and leave only what you really need.
How to use: paste the decompiled QC code into the textbox, select/deselect the checkboxes for commands that you want removed and extra cleaning and clic "clean the crap!" button, copy/past the code back to your QC file.
Note that once you clean your QC code, you won't need the "idle.smd" nor the "physmodel.smd" file that the mdldecompiler generated if "$colllisionmodel" and "sequence(idle)" are checked.