I'm creating a tool to change some 'Map Document Properties' (for example Title, Description, Author), with arcpy (it can also be model builder, or both), to execute from a personal toolbox.

But I want to know if is it possible to show the actual information of the property I want to change at the tool window, before I run it. Just like the 'Project' tool does. It reads the input coordinate system, and show it:

I think it could be something like 'print', but to work before run the tool, and display it... But I do not know how to do it.

This way, I could run it in a batch mode, and easily see the mxd's that I really need to update, and the ones already updated.

It would be something like this:

Input mxd

MXD 'Map Title' (given)

MXD 'Map Title' Change (optional)