How to create a checkbox parameter in a ArcGIS custom Python tool?

To see how to get a checkbox onto the dialog of a Python script tool try using some test code like this:

inputString = arcpy.GetParameterAsText(0)
inputBoolean = arcpy.GetParameterAsText(1)

arcpy.AddMessage("String set to " + inputString)
arcpy.AddMessage("Boolean set to " + str(inputBoolean))

Then when you add this script as a tool you will need two Parameters, the first of Data Type String and the second of Data Type Boolean.

A sample code for a script tool which will have a single check box. If a check box will be checked by a user, the tool will verify existance of a specified data file.

import arcpy
input_fc = r'C:\GIS\Temp\data_shp.shp'

    #getting the input parameter - will become a tool parameter in ArcGIS of Boolean type
    ischecked = arcpy.GetParameterAsText(0)

    #Important to convert the check box value to a string first.
    #Should be 'true' with the small case for 't',
    #not the 'True' as shown in the Python window in ArcGIS
    if str(ischecked) == 'true':
        arcpy.AddMessage("The check box was checked")
        result = arcpy.Exists(input_fc)
        #to return 'True' or 'False' depending on whether the data file exists
        #since it is a Boolean, important to convert it to a string
        arcpy.AddMessage(str(result))

    else: #in this case, the check box value is 'false', user did not check the box
        arcpy.AddMessage("The check box was not checked")

Remember to add a tool parameter of Boolean data type when creating a new script tool in ArcGIS Desktop application. This parameter will be automatically shown as a check box when user runs the tool.