OpenAI Community
2026-08-13 16:15 UTC
Score 45.0
AI-116-20260813-social-media-be496b0a
Full article
We’ve been using gpt-5.6-luna lately in our production systems. I finally figured out that the pricing that is quoted is misleading. The claim is that the price is $0.20 per million input tokens. You pay 1.25x for write cache and 0.1x for read cache. You can choose explicit mode or implicit mode for caching. In explicit mode, you tag each input block that you want to be written to cache. Other inputs won’t be cached. In implicit mode, the system takes care of it for you. At least for us the main reason that this pricing is misleading is that, in practice, there is no real option NOT to use implicit mode. And that means that ALL of your input tokens are getting charged at 25% above that stated price (except for the cache hits of course). So you might say, “Well, just use explicit mode. You decide what to cache.” Yes, but there’s a big catch. When you use function tools (as we do extensively), each tool call generates tool results that have to go back to the model. And while implicit caching will work on those, there’s no way to mark these tool results as cacheable. Normally you wouldn’t think that a tool result would be cacheable. But remember that when making a chain of calls, the recommended process is to append the tool results to the end of the same input chain. So all of your stuff that didn’t appear to be cacheable, including those tool results, really needs to be cacheable for the subsequent steps in the same response generation (for each set of tool calls made by the…