Source code documentation generator tool.
Doxygen is a documentation system for C++, C, Java, Objective-C, Python, IDL (Corba and Microsoft flavors), Tcl and to some extent PHP, C#, and D.
As of version 1.7.5. doxygen does support Tcl directly (see doxygen+tcl).
It is also possible to write a filter that convert the Tcl source code in to something similar to C++. Doxygen can call this filter when it is needed.