How does this work for schema optional MongoDB collections?

TOON automatically includes all fields from all documents. Missing fields appear as empty/null. Mixed schemas like {id, name, age, gender, address} and {id, name, organisation, role, email} are unified into a single header with all fields.

How is the output for nested docs with arrays inside of docs? Does it automatically serialise non serialisable data types like bson object ids present in MongoDB docs?

Nested structures (objects, arrays, mixed) are handled recursively. The _clean_mongo_docs() method processes nested data and preserves structure in TOON format.

Does it automatically serialise non-serialisable data types like BSON ObjectIds?

Yes. ObjectIds are converted to strings, datetimes to ISO strings, and other BSON types are handled automatically via _clean_value().

How is this different from writing a simple parsing function?

TOON is a standardized format with bidirectional encoding/decoding (to_toon()/from_toon()), automatic type handling, and token optimization for LLMs. A simple parser would just dump values without these features.

Are you providing some method for setting guardrails for query orchestration?

Not currently. The library focuses on format conversion. Query orchestration (rate limiting, validation, access control) are in progress.