[aldanor]

YAML is one of the most ambiguous formats out there, and definitely an overkill for what's needed to describe metadata.

JSON - not the most convenient to use for human beings, too much quoting, not too git friendly because of disallowed trailing commas, etc.

TOML sits somewhere inbetween, easy to write but the spec is very short; also being used in Rust and a few other places.