The secret sauce part is the useful part -- the local vector store. Anthropic is probably not going to release that without competitive pressure. Meanwhile this helps Anthropic build an ecosystem.

When you think about it, function calling needs its own local state (embedded db) to scale efficiently on larger contexts.

I'd like to see all this become open source / standardized.

im not sure what you mean - the embedding model is independent of the embeddings themselves. Once generated, the embeddings and vector store should exist 100% locally and thus not part of any secret sauce