I've tried using the Xamarin Android SDK Manager on three different machines and each time, after installing relevant packages, using sdkmanager or avdmanager from the command line no longer works due to parsing exceptions. Example:
C:\android-sdk\tools\bin>sdkmanager --list
Warning: cvc-elt.4.2: Cannot resolve 'sdk:platformDetailsType' to a type definition for element 'type-details'.
Warning: cvc-type.2: The type definition cannot be abstract for element type-details.
Warning: unrecognized type name: {http://schemas.android.com/repository/android/common/01}platformDetailsType. Did you mean {http://schemas.android.com/sdk/android/repo/repository2/01}platformDetailsType?
Warning: Unable to create an instance of com.android.repository.impl.generated.v1.TypeDetails
Warning: Found corrupted package.xml at C:\android-sdk\platforms\android-25\package.xml
Should be reproducible by downloading the latest version of the Android tools (Direct) and Platform tools and then pointing the Visual Studio Android sdk location to the root folder where you unzipped the two archives. Use the Xamarin Android SDK Manager to install Android SDK Platform 25. Then from the command line run the above command. You should get the errors. If you run the command again, the sdk has corrected the suspect xml, but I've run into other similar parsing errors (during avd creation) that have not corrected themselves. Why are the files that the Xamarin Android SDK Manager installs different that what Google's sdkmanager.bat installs?