GPT-5.6

system2

At this point, they are just changing the decimals to stay relevant and in the news.

realty_geek

Wow, the "Agents' Last Exam" graph looks unreal!

sidcool

The claims are pretty bold. I think 5.6 may exceed Fable.

Syntaf

Ok long time Claude Code user here; lately I've started to realize there's other great models out there I should be trying, but I'm hesitant to leave Claude Code behind for something new. What's the consensus today on codex vs claude code, does it really matter anymore?

saberience

"On Agents’ Last Exam (opens in a new window), an evaluation of long-running professional workflows across 55 fields, GPT‑5.6 Sol sets a new high of 53.6, eclipsing Claude Fable 5 (adaptive reasoning) by 13.1 points. Even at medium reasoning, it beats Fable 5 by 11.4 points at roughly one-quarter the estimated cost. That efficiency extends to smaller models, which are essential to making intelligence more abundant and affordable: GPT‑5.6 Terra and GPT‑5.6 Luna outperform Fable 5 at around one-sixteenth the cost. " Some pretty big claims and results! Excited to see how it feels during usage. I use Fable and 5.5 extensively and I still find both have a place in my toolkit, i.e. Fable IS good but it isn't perfect, and it's still better to play them off against each other. I have Fable and 5.5 write plans and have them adversarially review each other's plans. Having this amount of competition in the coding model space is good for all of us.

tipiirai

Thought Fable was great

rvz

Most importantly, the cost: > GPT‑5.6 is priced per 1M tokens across three model sizes: Sol is $5 input / $30 output; Terra is $2.50 input / $15 output; and Luna is $1 input / $6 output. Just as expensive as Fable 5. But of course, another slot machine upgrade but the costs will keep going up and the open weight models from china will continue to race everyone else to $0. Looking forward to the next version of GLM, Qwen, Deepseek and Minimax.

sd9

I haven't tried an OpenAI model for a long time, but with Fable going to API pricing soon this might be enough to get me to try codex.

cbg0

5.6 Terra (mid tier model) as good as Fable on DeepSWE while cheaper than Opus API pricing. Seems like a homerun.

minimaxir

The developer's guide ( https://developers.openai.com/api/docs/guides/latest-model ) has some interesting semantic tips for using the model: > Intent understanding: GPT-5.6 can better infer the user’s underlying goal and intended level of work without you specifying every step. Continue to state important constraints, approval boundaries, and success criteria explicitly. > Original image detail: GPT-5.6 preserves the original dimensions of images sent with original or auto detail instead of resizing them to a patch budget or pixel-dimension limit. > Use shorter prompts: In internal evaluations, replacing long, explicit system prompts with minimal prompts improved scores by roughly 10–15%, while reducing total tokens by 41–66% and cost by 33–67%. > Avoid generic brevity instructions: GPT-5.6 is more sensitive than GPT-5.5 to instructions such as “Be concise,” “Keep it short,” or “Use minimal text.” > Control warmth: GPT-5.6 does not become meaningfully better when prompted to be broadly friendlier or more empathetic.

willchis

The marketing team must've done research that said "people are starting to think that you guys are evil-water-stealing-lay-off-loving-bubble-bursting scumbags" and decided to really lean into the small family business and happy font vibes!

enraged_camel

CTRL-F: Fable 15 hits Holy shit. They must be feeling very threatened by Fable if they're spending this much energy talking about it in the release notes for their own model.

dude250711

Not available - checked and it's not there.

therobots927

Do they expect us this model is 15ppt more accurate at half the price of fable? What’s going on?

arizen

"GPT‑5.6 delivers a step change in design judgment. With only high-level direction, GPT‑5.6 creates tasteful, ergonomic, and functional interfaces. Its stronger computer-use capabilities let it inspect and refine the rendered result—not just generate the underlying code or content—so it can catch visual and functional issues and apply finishing touches before handing the work back." This one is really promising, as it may allow to close major gap with Claude in design/UI skills

eig

Funny to see that they did not include Fable 5 in their GeneBench and LifeSciBench comparisons because "it does not answer advanced biology questions and refuses the majority of questions in this eval". Winner by default!

newfriend

>Even at medium reasoning, it beats Fable 5 by 11.4 points at roughly one-quarter the estimated cost. Sounds great. Also latency looks very good.

GodelNumbering

Dirac ( https://github.com/dirac-run/dirac , https://dirac.run/ ) now supports gpt-5.6. This thing does now seem to be on the chatGPT/codex accounts yet. UPDATE: it is now available in chatGPT account also, they rolled it out

hughw

If it's not dangerous enough to be classified as WMD by USG, who's interested.

big_toast

The cost & output token charts are useful but I wish I could view them more like a 3D surface. Like the CS:APP memory mountain charts. I wonder how long model size and effort will be a few discrete points instead of continuous.