The Python Tools menu contains tools to export .fbx files, select characters and control keys, and run batch scripts. You can invoke all these tools through the Python Tools Manager.
The Python Tool Manager stores a list of all custom MotionBuilder tools you created using Python. If you want to access a custom MotionBuilder tool that is not displayed in the UI, instead of running the script used to create the tool, you can access the tool via the Python Tool Manager.
You can save or export .fbx files created in MotionBuilder 2013 to an earlier version of FBX by selecting Python Tools > FBX Export > FBX 2010, 2011, or 2012.
The Character Selection/Key Controls tool script allows IK, FK, Effectors selection and keying, and allows keying FullBody, Body part and selection without changing the keying mode.
You can find the Python UI-based batch tool script (BatchTool.py) in the MotionBuilder root directory under the bin\config\PythonStartup\ folder.