Power Tools are combinations of markup types with user defined colors that trigger special functionality like citation lookups and table recognition. Power Tools are therefore a handy way of speeding up research tasks you do often in Highlights.
Open Preferences, go to the Power Tools-pane:
Find the desired function and click the No default color-button next to it. Choose a color from the popup-menu:
Here is an example of what the pane can look like when all the power tools are set:
When a color is set for a power tool, any annotation you add with this markup type and color will automatically trigger the functionality defined here.
In other words, with the above settings, if you underline a citation with the purple color like this:
This will trigger a citation lookup and if successful your note will be updated with a citation without any additional steps:
Similarly, if you make an image selection over a table using green (with the above settings):
Table recognition will be triggered and if successful your image will be replaced with a table without any additional steps:
Keep in mind that power tools work for both new and existing annotations in the PDF, so the colors chosen should not conflict those used for regular annotations.