Not surprisingly, I get a lot of requests for ArcGIS products to provide similar functionality to Tableau dashboards. One request in particular that I get is to customize the tool tips that display when you hover over a data point in a chart. Right now, there doesn't appear to be much control over what is included in the tooltip beyond the column name and a second row with "Sum of {columnname}" or "Count of {ColumnName}" depending on what summary statistic being used.
I would like to be able to add custom text to the tooltips, much like what you can do with pop-ups. At the minimum, it would be nice to be able to change the data labels for the statistics. Even better, it would be great if I could write a sentence like we can already do in map pop-ups. So, instead of
ColumnA: Value
Sum of ColumnB: Value
It could say, "In Nowhere County, 17 samples were collected."