System architect at AraxaTech
I don't have any idea if mono-tools is still supported package, but its build is badly broken at least on FreeBSD. Anyway, the only tool I find really useful there is monodoc, which luckily can be installed manually like this:
After all this you should be able to start monodoc from command line (or to invoke it from within monodevelop using F1). I find monodoc very useful when browsing Gtk# documentation, since web documentation seems to have some very stupid layout.