CUE is an open source language, with a rich set of APIs and tooling, for defining, generating, and validating all kinds of data: configuration, APIs, database schemas, code, ... just name it!...
This approach breaks down, of course, if the restrictions in are too stringent and jobs need to override them. To this extent, CUE provides mechanisms to allow defaults, opt-out, and soft constraints...
The usefulness of a language may depend on the scale of the project. Having too many different languages can put a cognitive strain on developers, though, and migrating from one language to another as scaling requirements change can be very costly. CUE aims to minimize these costs by covering a myriad of data- and configuration-related tasks at all scales.