1import arcpy
2mxd = arcpy.mapping.MapDocument("CURRENT")
3df = arcpy.mapping.ListDataFrames(mxd, "*")[0] # grab 1st dataframe in map
4#df = arcpy.mapping.ListDataFrames(mxd, "Main")[0] # grab dataframe named 'Main'
5arcpy.MakeMosaicLayer_management(
6 'Orthophotos', # input mosaic
7 'test_mosaic', # output mosaic
8 '#', # Optional WHERE clause
9 df.extent # clipping box coordinates
10 )