问题:

Any idea why I'm not getting any documentation to go along with my ReSharper IntelliSense? If I go to the ReSharper options and enable the Visual Studio IntelliSense instead, I get the proper documentation when going through the members in the IntelliSense pop up. If I re-enable the ReSharper IntelliSense, I now get the ReSharper IntelliSense pop up sans documentation.

回答1:

Go to ReSharper | Options -> Environment | IntelliSense | Completion Appearance. Check Show member signatures and Show summary.

回答2:

For those who, like me, tried the solution provided above and it didn't work. I found this article and it did the trick for me.

Go to Tools - Options - Text Editor - C# (or all Languages, or whatever you need). In the general section, the options Auto list Members and Parameter information must be enabled. (I suppose only Parameter Information would be fine to, but i enabled the other one anyway as its a nice feature).