To add text to the Description field:

Open the script in Script Editor.

Click Description at the bottom of the script window.

Type the desired text.

Save the script.
You can type a description of a script in the Description field at the bottom of the script window. If you save the script as an application and select the Startup Screen option, the text in the Description field will appear in a dialog when the script is run.
Open the script in Script Editor.
Click Description at the bottom of the script window.
Type the desired text.
Save the script.
Formats such as font type, size, style, and color can be applied to the text in the Description field by selecting the text and using the editing tools in the Font menu.