Yes, minified JSON would be even less tokens than YAML. But: 1- LLMs tend to have very hard time to produce minified (compacted) JSON in the output, consistently. 2- As for compacted JSON input- Empirically it seems that LLMs can process it quite well for basic cognitive tasks (Information Retrieval, basic Q&A, etc), but when it comes to bit more sophisticated tasks it fails compared to exactly the same input, uncompressed. I've mentioned and provided examples in the comments of this article.