The ability to annotate a visualization, for example a chart or graph, would make both the dashboard and reports experience more robust.
The ability to add annotations/narratives to visuals when certain slicer sets are selected or levels are shown on the visual as part of bookmarks or as part of user interactions would be very useful. An example would be looking at sales across the year and noting an uptick in the 3rd quarter, when you drill into the third quarter noting that the uptick was because of a new product category and this has to be stripped out to see the underlying trends. The ability to then add annotations when regions are added or drilled into to reflect which regions were impacted by internal business outages for example. Having these narratives added to bookmarks would enable more effective storytelling and would also make them easier to discover and reproduce (users tend to find something then want to go discuss it with someone so need to find it again) some method of displaying these on screen is of course critical.
