Claude Opus 4.8

A rambling comment:

I think this is the first time we've had a third minor version bump on a frontier Anthropic model. (I count the 0.5s as major here, because they've been issued non-sequentially and also corresponded to massive capability leaps, eg, Sonnet 3.5, Opus 4.5).

So now the Opus 4.5 family has successors 4.6, 4.7, and 4.8, each posting fairly modest claimed gains. My own experience w/ 4.6 and 4.7 are that I don't firmly grasp any capabilities improvements over my memory of 4.5, but it's all so fuzzy that it's truly difficult to tell.

Maybe my own tastes are saturated now (it's smarter than me?) and I'll never again perceive model progress. Maybe the incrementalism is such that I'd notice immediately if my 4.7 workflows were redirected now to 4.5.

Difficult spot for the labs to be in because, if they have a stronger product, I'd prefer they release it and that I can use it.

But as this dynamic continues, the improvements are going to be less and less legible for end-users, who will complain about the churn-without-payoff, even when the payoff may actually be real.

My fav coding benchmark for frontier models is to build a simple RTS game in one file (js/html/css). Claude Code with Opus 4.8 in ultracode mode nailed it, the best result so far:

https://bsky.app/profile/senko.net/post/3mmwnrkwboc2v

The prompt was: Create a simple but functional real time strategy (RTS) game similar to old WarCraft, StarCraft or Command & Conquer games. The player should be able to build buildings, create units, gather resources and should uncover the whole map. No AI or multiplayer needed. Use simple but nice-looking graphics. No sound. Implement everything in HTML/CSS/JS, everything in a single file (you can use 3rd-party js or css libraries/frameworks via CDN).

"Users will find Opus 4.8 to be a modest but tangible improvement on its predecessor."

This is a refreshing attitude!

I've also verified that you can now turn off adaptive thinking in the web UI, which is great. I've had a lot of problems with thinking not triggering and the model producing sub-par output. Glad we can finally turn it off. (I hope being able to turn off adaptive thinking is new, if I could have turned it off at any time that would be embarrassing)

> Not only that, but we plan to release a new class of model with even higher intelligence than Opus. As part of Project Glasswing, a small number of organizations are currently using Claude Mythos Preview for cybersecurity work. Models of this capability level require stronger cyber safeguards before they can be generally released. We’re making swift progress on developing these safeguards and expect to be able to bring Mythos-class models to all our customers in the coming weeks.

Probably more interesting than the 4.8 release.

I generated pelicans riding bicycles on both thinking level low and thinking level high:

https://gist.github.com/simonw/68560eddb0b268a8417f80ceb7304...

The high one is notably better - the bicycle frame is the correct shape, unlike thinking level low.

For comparison, here's Opus 4.7: https://gist.github.com/simonw/afcb19addf3f38eb1996e1ebe749c...

As if choosing a model to use on its own is not hard, offering six levels of "effort" (quite a vague term as well), low, medium, high, xhigh, max, ultracode (?!?!) is really making comparisons next to impossible when people using the same model can have vastly different experiences.

What exactly is the diff between high and xhigh? Or xhigh and max? This is definitely too granular and it seems Anthropic took OpenAI's confusion with models as inspiration.

Early ArtificialAnalysis.ai results show GPT 5.5 is still the better bang-for-your-buck.

OpenAI solves tasks with about 50% less output tokens.

https://artificialanalysis.ai/?intelligence=coding-index&int...

Meanwhile Deepseek is cutting inference costs to mere cents. Thats the real AI revolution for you.