I am looking at this documentation for post processing validation resource within a python toolbox and it utilizes the arcpy.mp module for manipulating the contents of existing projects (.aprx) and layer files (.lyrx). The example in that link above makes it seem that arcpy.mp can be used inside a python toolbox. However, I'm reading that arcpy.mp requires that some methods and properties only work when ran inside the python pane or a script tool inside of ArcPro (ArcGISProject object resource ). Does the arcpy.mp only work when its a geoprocessing toolbox and not a python toolbox thats executed in an IDE?