Did a migration myself last week from using playwright mcp towards playwright-cli instead. Which has been playing much nicer so far. I guess you would run into the same issues you've already mentioned about running chrome headless in one of these sandboxes.
I really don't have any numbers to back this up. But it feels like the sweet spot is around ~500k context size. Anything larger then that, you usually have scoping issues, trying to do too much at the same time, or having having issues with the quality of what's in the context at all.
For me, I would say speed (not just time to first token, but a complete generation) is more important then going for a larger context size.
From my point of view, you're either choosing between instruction following or more creative solutions.
Codex models tend to be extremely good at following instructions, to the point that it won't do any additional work unless you ask it to. GPT-5.1 and GPT-5.2 on the other hand is a little bit more creative.
Models from Anthropics on the other hand is a lot more loosy goosy on the instructions, and you need to keep an eye on it much more often.
I'm using models interchangeably from both providers all the time depending on the task at hand. No real preference if one is better then the other, they're just specialized on different things
> The last thing I'll mention is that Claude Code (Sonnet 4.5) is still very token-happy, in that it eagerly goes above and beyond when not always necessary. Codex (gpt-5-codex) on the other hand, does exactly what you ask, almost to a fault.
I very much share your experience. As for the time being I like the experience with codex over claude, just because I find my self in a position where I know much sooner when to step in and just doing it manually.
With claude I find my self in a typing exercise much more often, I could probably get better of knowing when to stop ofc.