Once upon a time, the “Require a Changeset Comments” check-in policy for TFS came in the TFS Power Tools. In Visual Studio 2012, they rolled that policy into the Visual Studio distribution. Now, the check-in tool from git-tfs cannot find it. To solve that problem, you need to make the check-in policy available to git-tfs.
C:\Program Files (x86) Microsoft Visual Studio 11.0 Common7 IDE CommonExtensions Microsoft TeamFoundation Team Explorer
git-tfs installation directory. That should allow the check-in tool to
find the policy.