There are a number of semantic layer tools out there these days. Each has their own unique approach, but essentially it's a meta layer on top of your database that can be used to do things like form queries or provide a consolidated API to your data (which may be in multiple databases).

Some comments on this thread mention popular semantic layer tools like cube.dev. I also made an open source one that I use regularly, though it's currently in I-hope-to-put-more-time-into-this-someday mode. Been busy with an acquisition this year.

https://github.com/totalhack/zillion

Not OP, but a naive guess is it would mean that you'd have your schema defined in an ORM (for example, Prisma). The advantage here is that the LLM gets context on both the schema and how the schema is used throughout the application.

I use Weaviate and let the model create GraphQL queries to take advantage of both the semantic and data layer. Not sure how efficient it is but it's worked for me