Yes that would appear in the help command in the ddl command group next to describe, although it shouldn't be confusing since desc is the widely known common shortcut for describe across various systems and I've intentionally inherited from Describe so the help documentation and implementation is exactly the same and will inherit any changes made to Describe in the future.
Right now the code wouldn't support a regex without a more significant rewrite of the hbase shell. It's all pre-defined command lists which are just dynamically eval'ing the command files for the command classes containing the actual command method for the action. A regex wouldn't know where to find the actual class definitions.
If you leave desc off the pre-defined command list it never loads the desc class. Even if you move the Desc class to describe.rb which is loaded you don't get the command mapping and end up with an error "NoMethodError: undefined method..."
The command mapping is a class inheritance variable in the base Shell module, so the only other reasonably easy way that I can see to do this would be to add a special case in the base Shell module, which is slightly more hackish way of doing it and not in keeping with the current command framework, although the desc command will not show in the ddl group for help, it'll be a stealth shortcut.