TFS picking a version to use
 

I am running a get action on a build machine with VS2012 and VS2013 installed, when I run the actions for a get from TFS its seems to always run for version 11(VS2012).

Is there a flag that I can set in the script that I can set per script to use a different version of the command line tools, I am using VB 8.1

By default, it should run the highest installed version of TFS (in my tests, it does run the VS 2013 [12.0] version when installed), but you can specify which tf.exe to call via the last field on the Options tab.
http://kinook.com/VisBuildPro/Manual/teamfopttab.htm

thanks, but I am still not sure why if I have both installed its defaulting to the older version

I did find a global variable DEVSTUDIO_NET_DIR it points to 11 not sure why? Is this variable calculated each time VB is opened?

I was running 8.1 that might be the issue, I updated to 8.7 and now its defaulting to version 12

That macro is not used by the Team Foundation action, and it is not automatically updated -- use Tools | Application Options | File Locations -> Reload to update it.