Decomposition Tree Unique Description Tooltip required

Hi All, 
I'm struggling to find a solution to meet a clients' request to display a unique description (tooltip) on each item within a decomposition tree.

In the example screenshot below, if I hover over Abilities in the CertificationName level, I want to show just a description for that item.
Likewise, if I hover over 'Assessments' DomainName, I just want to show the descriptive text for Assesments.

I am free to chaneg the data model if required to make this possible... Is it possible??

Any help greatly received.

Cheers,

Rick