C:\"Program Files (x86)"\"Microsoft SDKs"\Windows\v8.1A\bin\"NETFX 4.5.1 Tools"\ Generate a .dbml file that includes extracted SQL metadata:
sqlmetal /server:myserver /database:northwind /dbml:mymeta.dbml

SqlMetal.exe /code:Northwind.cs /context:Northwind /namespace:nwind Northwind.dbml
Rather think this does not function as described from 2012 to 2017.
Seems when you create an ADO.Net Entitity Data Model you have to go with EF Designer rather than Entity Framework Reverse Engineer Code First plugin on the Project.
Further Reading ...
Mentions WG.EXE - WebGrease