While I am trying to Install API 18 it shows only \"Google API 18\"
(nothing more). Now if I try to install these google APIs from Android SDK Manager
I had this problem with API 19. The key for me to use the Android SDK Manager starting in eclipse. Then, the advice above worked to fix the issue.
Background: Because of other command line stuff I was doing, I was starting the SDK Manager by typing "android" at the prompt. - which is what the error I was getting said to do.