I've been testing Sol/Terra/Luna now since yesterday, running complex evals on all of them and I feel a bit... mixed on how they perform.
The eval is an agent that runs a set of tools and a prompt we can tune separately for different models. The OpenAI version of the prompt was specifically tuned based on their guide[0]. Then we let Opus to run another agent that acts as a user, trying to solve a problem (anonymized and taken from production). The problem is complex and we don't expect it to be solved by these agents, but we measure how the agents operate when faced with a vague problem:
- Opus 4.8 and GLM 5.2 both identified a constraint sooner and stopped so the user can fix an issue first that the agent cannot solve.
- Sol tried hard to solve the issue with different tools, burning tokens, until finally reached to the same conclusion with Opus and GLM. It was two times more expensive compared to Opus and six times more expensive to GLM for this task.
- Terra went even further and started calling tools that would not solve the issue, burning tokens and failing.
- Luna repeated the same failing tool call until it hit the round limit, and burned more money than Opus.
I'm kind of puzzled with the new GPT. Like, yes Sol is OK for programming, but I was expecting to get a cheap agentic model for non-programming tasks, one that can detect if things go awry and correct. Terra is too expensive and Luna not really fit for the task. Sonnet 5 is a bit better but more expensive than Opus 4.8, which is still the best in my evals. GLM 5.2 is extremely good if you can define the task and the tools clearly for it, and costs pennies!
[0] https://developers.openai.com/api/docs/guides/latest-model
Yes, this is exactly why I said yesterday that OpenAI does benchmaxxing, seemingly quite a bit [1]. I got a flurry of downvotes for it at first, but I think people came around to it once they tried the model like you did.
Ultimately I think the issue is that OpenAI is under tremendous pressure to perform, but GPT-6 is not ready yet, so they had to push GPT-5 to its limits, and the only way they could do it was with really heavy RLHF, which has its shortcomings. Like, it is super obvious that Sol, Terra and Luna are all heavily biased towards working on a problem relentlessly because that's what their reward functions emphasized. That pushes up their scores in some benchmarks but does not translate to actual intelligence and capability.
I thought I was an OpenAI fanboy, but version 5.6 isn’t for me. Sol Ultra just keeps working and checking, and working and checking again, but it can’t even correct minor errors that aren’t a problem for 5.5 xhigh. I’ve rolled Codex back to 5.5 for now.