Yes definitely. But this is to be expected. Heck take the same person and put them in two different environments and they'll have very different performance!
> But cross (same tier) model in the same agent is much less stark.
Unclear what you mean by this. I do agree that the big three companies (OpenAI, Anthropic, Google DeepMind) are all more or less neck and neck in SOTA models, but every new generation has been a leap. They just keep leaping over each other.
If you compare e.g. Opus 4.1 and Opus 4.5 in the same agent harness, Opus 4.5 is way better. If you compare Gemini 3 Pro and Gemini 2.5 Pro in the same agent harness, Gemini 3 is way better. I don't do much coding or benchmarking with OpenAI's family of models, but anecdotally have heard the same thing going from GPT-5 to GPT-5.2.
The on the ground improvements have been coming primarily from model improvements, not harness improvements (the latter is unlocked by the former). Again, it's not that there were breakthroughs in agent frameworks that happened; all the ideas we're seeing now have all been tried before. Models simply weren't capable enough to actually use them. It's just that more and more (pre-tried!) frameworks are starting to make sense now. Indeed, there are certain frameworks and workflows that simply did not make sense with Q2-Q3 2025 models that now make sense with Q4 2025 models.
