Add public note when task is completed

Hi, not sure if anyone has come across this and can point me in the right direction…

I have a basic workflow that adds a public note to a ticket when a task within the ticket is marked as complete. When adding placeholders, there is an option to add fields from the task. I have tried adding

{{ittask.description}}

{{ittask.title}}

but neither show up when the note is added. Is there a way to add the details of the task that has been completed to a public note on the corresponding ticket? 

Thanks in advance. 

Kevin.