In Microsoft and Unity's continuing efforts to make life easier for game developer, the latter has finally integrated Visual Studio debugging into its IDE, meaning users will no longer have to separately install the Unity Tools extension -- it'll just work out of the box.
The only downer is you can't do it just yet. According to Unity dev Lucas Meijer, it's now a part of version 5.2b3 of Unity's beta builds:
hey #unity3d folks, the 5.2b3 build has builtin UnityVS/VSTU support. Debug in visualstudio! I'd love to hear feedback on how it's working
— Lucas Meijer (@lucasmeijer) July 23, 2015
A further comment by Meijer points out that it's only for Visual Studio 2015, but that's not terribly surprising. It does mean if you're using a previous version, it might be time to look at upgrading if you can.
Although it was never much of a hassle to install the extension separately, it does make Unity's included version of MonoDevelop even less appealing than it already was.