At present, when content arrives from one of the load-on-demand mechanisms in RadToolTipManager (AJAX request, web service, WCF web service), it is expected that it has static dimensions that match those set in the Width and Height property of the control.

Having an autosizing feature similar to RadWindow's should let it update its size (e.g., height by provided width) and position according to the new content when it arrives.

Samples are attached that showscase examples of resizing the tooltip once content arrives so you can use as base and implement similar resizing logic by calculating the dimensions of the content that came back.