Archive. The Build Tools are no longer sold or developed. The documentation stays online for everyone who still uses them.
What were the Microsoft Dynamics AX Build Tools?
The Build Tools packaged and delivered development states of Microsoft Dynamics AX 2009 and 2012, using Team Foundation Server 2015 Update 2 (or later) or Visual Studio Team Services. The necessary steps were assembled on a modular basis and then ran automatically.
More about build automation at Microsoft: https://www.visualstudio.com/en-us/get-started/build/build-your-app-vs
Build template example
Build steps
Extension in the Marketplace
The extension for Visual Studio Team Services and Team Foundation Server can still be found in the Visual Studio Marketplace.