There is no visual studio solution for building the tools (mongodump, mongoexport etc) that come with MongoDB. The text on GitHub specifically mention these tools as being present in the repo and point to the build instructions file. The build instructions point to a docs article on building on windows:
With Visual Studio: http://www.mongodb.org/about/tutorial/build-mongodb-with-visual-studio-2010/#build-mongodb-from-the-ide
With SCons: http://www.mongodb.org/about/tutorial/build-mongodb-with-visual-studio-2010/#build-with-scons

The SCons method will incidentally build the tools. The Visual Studio solution does not contain tools projects, nor do there appear to be any tools projects in the repo at all.

This difference should be rectified (or clarified as intentional so the docs can be updated instead).