Comments don't seem to be allowed in the tsconfig.json file. See this article for why it is ok according to Douglas Crockford to add them to json config files.

I initially raised this issue with gulp-typescript as I'm trying to use that Gulp task in my ASP.NET 5 project to compile my .ts files to .js but I'm getting errors and the developer has pointed me here.

My goal is to add TypeScript support to ASP.NET MVC Boilerplate which provides an ASP.NET 5 project template with lots of helpful comments and features built in. I'm currently having to resort to a separate tsconfig.html file to write comments about the file. The comments include a little info about what the file is for, a useful link to the tsconfig.json documentation and a few reasons for the chosen default settings.

Many other similar json config files already support comments. Examples are: JSHint (.jshintrc file), JSCS (.jscsrc file), TSLint (tslint.json file). The first two do not use a file with a .json file extension which may have something to do with the use of comments.