Looking at pricing, its $15 per 1M input tokens, and $60 per 1M output tokens. I assume the CoT tokens count as output (or input even)? If so and it directly affects billing, I'm not sure how I feel about them hiding the CoT prompts. Nothing to stop them from saying "trust me bro, that used 10,000 tokens ok?". Also no way to gauge expected costs if there's a black box you are being charged for.