[Bug]: Utilities' toString method should consistently go between yml and JSON

[corinagum]

Related to #1171

Language

Javascript/Typescript

Version

latest

Description

Currently, Utilities.ts's toString method will (if toJSON is not specified) return whichever is shorter: yml or JSON. However, we think that the method should consistently return one or the other, not a (seemingly) arbitrary decision between the two, as this may confuse developers.

Instead of calculating which is shorter, toString should return yml. The current perception is that yml will normally be shorter than JSON and is more human readable, and LLM's seem to work a little more nicely with yml.

Reproduction Steps

run test: it('should convert a simple object to yaml', () => {
       const result = Utilities.toString(tokenizer, { a: 1 });
       assert.equal(result, 'a: 1\n');
 });

Note that this test fails; JSON is produced instead. Using gpt3.5/4 encoding, JSON and YML would be equal in token length.