I know that the purpose of the ArcPy GetParameterAsText function is to return parameters as text, but what is the benefit of doing that?

  • How do you find the list of parameters? (from arcpy.GetParameterAsText(0)) I've inherited scripts from a predecessor that uses this a lot, and I need to be able to edit these parameters to provide new/different options in the dropdown that the user sees. I'm new to python, arcpy. Can read most of it and understand what's being asked, but I can not figure out where the parameters come from, to be able to update them as needed.
    – B Hendee
    May 20, 2022 at 14:52

2 Answers 2


The summary on the Esri GetParameterAsText documentation states:

Gets the specified parameter as a text string by its index position from the list of parameters.

Functionally this allows you to pass arguments to a Python script tool. Script tools allow you to provide custom functionality in a GUI to those who do not want to use Python.

The documentation also provides an example of the usage:

import os
import arcpy

# Set the input workspace, get the feature class name to copy
#  and the output location.
arcpy.env.workspace = arcpy.GetParameterAsText(0)
in_featureclass = arcpy.GetParameterAsText(1)
out_workspace = arcpy.GetParameterAsText(2)

out_featureclass = os.path.join(out_workspace,

# Copy feature class to output location
arcpy.CopyFeatures_management(in_featureclass, out_featureclass)
  • so in this example the tool dialog box would have those three parameters that are prompting the user to input? Also, is the os.path.join trying to join different workspaces?
    – Ryan Mags
    Nov 22, 2019 at 4:54
  • 1
    Yes, the script tool dialogue box would have those three parameters which the user can input in the script tool. os.path.join() is combining the workspace path (e.g. /path/to/your/geodatabase.gdb) and the basename (e.g. some_name) to produce /path/to/your/geodatabase.gdb/some_name
    – Aaron
    Nov 22, 2019 at 4:58

In the ArcGIS Pro Help for arcpy.GetParameterAsText() its Summary is that it:

Gets the specified parameter as a text string by its index position from the list of parameters.

The way I think of it is that it is the means used to communicate, as text rather than objects, the choices made by an end user from the tool dialog that fronts a Python Script Tool of ArcPy.

The first parameter that the tool's author configures on its tool dialog is referenced from the script by using an index of 0 i.e. arcpy.GetParameterAsText(0).

There is an alternative way to reference the first parameter on the tool dialog, and that is as sys.argv[1] but that has limitations in the number of characters that it can accept whereas arcpy.GetParameterAsText() has no character limit. The two alternatives are documented in Accessing parameters in a script tool.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.