When you are using MSBuild, sometimes there is no specific task that provides the functionality that you need. At those times, you will have to use one of the many existing tools that can and should be used to assist in builds and deployments. Some of the most commonly used tools include FxCop, StyleCop, NUnit, and so on. In this chapter, I will describe how external tools can be effectively consumed by MSBuild. We’ll examine a few commonly used tools and discuss how to integrate them into your build process. We’ll first describe how these can simply be invoked in build scripts and then describe a way to create reusable targets files for tools. Also, we will discuss some guidelines for reusable build scripts.