I updated Eclipse with the new SDK tools (rev. 23), but now when Eclipse starts I receive the error:
This Android SDK requires Android Developer Toolk
There is a lot of confusion going around in this thread. There are two solutions depending on how you installed ADT.
If you installed the ADT plugin manually then I believe you can use the "Delete ADT" -> "Install New Software" approach.
If you are using the ADT Bundle then do not follow that solution! You will break Eclipse. Here is an update from a Google member - read #18:
https://code.google.com/p/android/issues/detail?id=72912
You must download a new version of the ADT-Bundle (yep, it's frustrating!).