Modify a page using a button in MediaWiki

Question

I'm trying to make a to-do list using MediaWiki. I'm using Semantic MediaWiki with a boolean property "Is Completed" so the jobs that are done don't show up in my to-do list:

I'd like to add a button (or checkbox, or something) on each task page that would modify the page to change the code

{{#set:Is Completed=false}}

to

{{#set:Is Completed=true}}
{{#set:Completed On=<TODAY'S DATE>}}

I've tried searching, but haven't found a straightforward way to do this. Is there any simple way to create a button which, when clicked by the user, runs a custom script that can modify the page?

Eventually I'll add another one to change it back to false, but that should be simple once I've got this part working.

Thanks in advance.