It has always been a problem that documentation in the source, where it should be, is not then passed into the live database when the build script is executed. In a table, you have columns, constraints and indexes that you are likely to document using line-ending comments and block comments. You probably have a big block comment at the start, explaining the table. This information should be available in the live database. Microsoft don’t have a good answer and vaguely go on about adding comments in extended properties. Well, that’s fine but it hasn’t happened, unsurprisingly: Have you ever tried to do it? It is an almost impossible task, even with SQL Doc.
My solution is to execute my finely-documented build script as usual to create the latest version of the database, and then process the same script in PowerShell to add all the comments and documentation as extended properties in the right place in the live database.
It’s an interesting approach to a classic problem.