Ed Elliott has created a tool to auto-name constraints in SQL Server Data Tools:
I have released a tool that will do just that, if you grab the SSDT-Dev Pack at least version 1.1 fromhttps://github.com/GoEddie/SSDT-DevPack/tree/master/release this adds a new menu to the tools menu in visual studio to name constraints. What I like to do is to go to “tools->options–>keyboard” and map an unused short-cut to the command “Tools.NameConstraints”, I used “ctrl+k + ctrl+n” so I can open a table in SSDT and just do ctrl+k and then ctrl+n and it automatically re-writes any tables in the active document that have unnamed primary keys with an appropriate name.