DSLs are a great middle ground for 'use LLM to turn ambiguous spec into something well defined', with the caveat that without discipline they'll inevitably expand until you should just have the agent write whatever the final language is.

There's a context tax up front (which will hopefully be less relevant over time) and then you really need a compiler/linter with helpful errors to keep it on the rails, because there is no corrective context in pretraining for something novel.

A purely descriptive DSL is just a convention, which is useful, but doesn't inject reliability the same way an enforced syntactic contract does.