You can add to a specific template and format it like this:
.Tooltip(tooltip => tooltip .Template("#=category# - #=value #") .Format("{0}%") .Visible(true) )
This will give you a tooltip that looks like this:
Hydro - 22%
I believe that using the template and format helpers together can lead to conflict, but you can add the format to the template as follows:
.Template("#=category# - #=kendo.format('{0}', value)#")
Alejo source share