Cato was specifically founded to advance libertarian views. They say so explicitly. They tolerate some open debate and have some intellectual honesty about it, but don't expect them to continue to fund or advance projects counter to libertarian concepts.

Brookings are pretty dang centrist, and I think there was actually a formal study on this point.

Anyhow, the point I'm making is that think tanks vary in how overtly political they are, but some like Cato and Heritage are very ideologically driven, and others like Brookings more reflect the selection bias of the status quo.