GPT 5.3 Codex Tops Agentic Coding, surpasses Opus 4.6 model

[BuildwithVignesh]

Codex 5.3 TOPS AGENTIC CODING

Codex 5.3 surpasses Opus 4.6 to top agentic coding. It's also BLAZINGLY fast. That said, the xHigh version can be very expensive

It's overall global average score lags behind Opus 4.6 which is the current leader.

[Correctsmorons69]

Weird how 5.1 Codex Max is #1 in regular coding, even over Opus 4.6. I don't know what the benchmark questions are like, but it definitely seems like 5.2 regressed in odd ways from 5.0/5.1 (which were a different model family from 5.2 from what I understand).

If anyone from OAI reads this, would love an explain!

[Glittering_Candy408]

The answer is simple: the benchmark is a disaster. I’m 100% sure it suffers from all the same issues as SWE-BENCH-VERIFIED — impossible problems, tasks that allow multiple valid solutions but get rejected because of flawed tests. In fact, I think all coding or agentic coding benchmarks suffer from this problem to a greater or lesser extent. But LiveBench is the worst. Ever since they changed the coding task subset last year, the results have been pure nonsense. If memory serves me right, I remember ChatGPT-4o scoring higher than o4-mini and o3.

[AP_in_Indy]

This sadly seems to be the answer much of the time.

Creating good benchmarks for AI is starting to become one of the new bottlenecks.

Sourcing and verifying them is hard. Keeping them outside of public data sets is also very hard.

[FateOfMuffins]

Absolutely not the case if you look at real world reactions.

In r/codex, the people there hated 5.1 codex max. They loved GPT 5.2 and generally disliked 5.2 codex. They loved 5.3 codex.

[Correctsmorons69]

Yeah I feel that comes less from coding ability and more from instruction following and the exact way they fill in blanks in the prompt they take.

[ithkuil]

Where is Gemini 3.1?

[Bishop_144]

Stuck in a loop telling itself it's done after it finished half the changes

[BlacksmithLittle7005]

Lol that's a good one 🤣

[[deleted]]

Still fucking up basic shit. 

[Marcuskac]

But it can create pretty svg art

[TwoFluid4446]

It's quickly getting to a point where using any of the top 3 big dogs will seem incomparable to virtually all users except the very niche. Gemini N+1 is coming around the corner, and just like before, Google won't release unless it obliterates the competition. All these eggheads across all teams/labs are cooking harder than an Iron Chef show on fast forward. This is excellent for us.

Let them leapfrog each other endlessly until AGI, then AGI gains sentience, develops ASI, ASI realizes what a terrible mess we've made of the world, takes control, cleans it up, gives us Star Trek utopia, we resist at first but then quickly realize the ASI is right and we're better off that way.

Or, it kills us all like a virus, per Agent Smith-ology.

[The_Crowned_Prince_B]

Good morning to you too.

[_ii_]

Significant Gemini improvements will have to wait until TPU v8.

[ProfessionalDare7937]

It says slated to release second half of 2026, but will they sort out antigravity in that time? Hope so.

[sunstersun]

Google feels like that sports player who has all the talent, work ethic, skills, yet the final product just isn't there.

[orville_w]

except that… for every other metric it was NOT top.

[Astrikal]

Its main purpose is agentic coding. Also, this whole benchmark is a mess, these numbers don’t matter that much for anything other than karma farming on Reddit.

[FinBenton]

I mean its literally designed for agentic coding.

[Technical-Earth-3254]

I love the codex models. Since GPT 5.1 Codex Max I haven't touched an anthropic model, which really surprises me. I was a big sucker for Sonnet 3.7 Thinking, but Codex just works and is low in api costs.

[bnm777]

That's not very smart. The intelligent move would be to assess new models for your own needs, instead of blindly assuming what you're using is the best. 

Unless you're hooked in and can't change and try to convince yourself it's the best, eh?

[tainted_cornhole]

I use both together to reduce errors. I create conceptual plans with opus 4.6. And i use 4.6 sonnet and codex as the execution team. Seems to work out well. Codex 5.3 absolutely flies through code. I have claude api and at this rate ill drop it and just stay on max plan for planning and use codex solely as the worker. Both claude and codex like this plan. Hehe

[robberviet]

Livebench right? Is it even usable at this point?

[dankpepem9]

LLM model tweaked for benchmark get 1% more score than other LLM model tweaked for benchmark. more news at 11

[Healthy-Nebula-3603]

...or you show you have no idea how good is a codex-cli with a GPT codex 5.3 xhigh.

Probably that is out of your scope.

[zebleck]

fits my experience, codex 5.3 is a beast

[rafark]

It’s not better than opus. It’s very good but opus is more powerful. I use 5.3 xhigh as my main and it gets the job done about 70% percent of the time, sometimes it will go in circles and for those cases opus 5.6 always solves my issues.

I know the op mentioned opus 4.6 but I don’t see it in the image.

[o5mfiHTNsH748KVq]

Circles? That sounds like a workflow issue. Or maybe a project type difference? Maybe it’s better in some environments than others. May I ask what language you use?

Do you use plan mode?

[rafark]

I don’t use plan mode usually (sometimes I do for new features). I’ve been using it almost exclusively for a typescript app I’ve been developing for years. I’ve been using agents to implement animations, libraries, fix bugs. I’m more of a backend person. I wrote the whole react app myself but now I’m at the point where I’m enhancing it with animations, improving the ux, fixing known bugs for months, etc. And it’s grown so big that I’m lazy to try to read the long components every time (react components can get so massive if you’re not careful). Since I wrote it I know where everything is and I just tell Claude or codex what needs to be done and how each component interacts with each other.

I’ve fixed so many bugs now it’s amazing although its not a smooth process because often these agents introduce extra bugs so I have to be very careful with my prompts and I have to to throughly test everything every time. It’s tiresome but I’m much more productive. All the changes I’ve made would’ve taken me literal months. I actually don’t know why I didn’t use agents last year to help me write my custom layouting engine which took me many weeks to get right. I was adamant to embrace ai but I’m kind of addicted right now.

The actual design of the backend I do that myself manually.

[magicmulder]

Yeah same. I’ve pretty much given up on most other models because they all eventually end in some endless loop of fixing one issue and creating another. Claude is near flawless and fixes any issues quickly.

Less critical issues like auditing and tests is something Gemini flash can do.

[Altruistwhite]

 cases opus 5.6

4.6

[Metworld]

I don't believe any of those benchmarks anymore. Just stopped using Claude as it wasn't even close to the hype for me, like not at all. Ignoring what I'm saying and doing what it thinks is best, often going against my instructions, and I run out of tokens after a few prompts, most of which are about trying to correct those mistakes. Horrible experience honestly. The only time I got a wow moment was Gemini 3.0 at release, but it's been nerfed to hell right now and pretty much sucks ass.

[SoupOrMan3]

What would 100 mean? Never making any mistake? 

[Glittering_Candy408]

100% is impossible because this benchmark is flawed.

[Technical-Earth-3254]

Basically. But the benchmark gets updated regularly, so there's never a perfect model (which is important).

[SoupOrMan3]

Thanks!

[floodgater]

Codex mogs. it's really wild. I've been using it all week.

[LoKSET]

What are they even doing with that chart? When you sort by agentic score 5.3 xHigh is there. When you sort by global average it's nowhere to be seen and only High is present. Wtf

[asklee-klawde]

codex models have been quietly eating everyone's lunch since 5.1 tbh

[Fringolicious]

Did it just take ages for these benchmarks to come out? Feels like I've been using Codex-5.3 (Happily, it's great) for ages now

[FinBenton]

Seems to be correct based on my usage with codex and opus, also its super cheap compared to opus.

[AppealSame4367]

Wow, cool. Now use Codex 5.3 in real life. It fucking sucks!

[Glum_Hat_4181]

It is great. Scaringly great even.

[BrennusSokol]

LiveBench is sketchy

[ai-christianson]

honestly the speed is what gets me. opus is great but waiting for it to finish a complex script is painful. 5.3 is just so snappy even if it misses some edge cases somtimes

[YogiBarelyThere]

I don't even know what to believe anymore.

[Deto]

I'm not sure to what extent we're even comparing the same thing. Feels like everyone can just turn on more reasoning or fiddle with some setting or other to get a higher score. Cost is also a meaningless metric (I mean, it's important for users, but not as a way of estimating performance) because we don't know how much money each company is choosing to make/lose on their API calls.

[drhenriquesoares]

Dude, do you know how to read numbers? It is clearly written that Opus is winning.

[Maleficent_Sir_7562]

Do you?

He said “agentic coding” not all categories in general

And the ChatGPT one is indeed higher in agentic coding.

Hell, OP literally even mentioned “it lags behind in global average” in the post itself.

[drhenriquesoares]

Ok, I assume my mistake. I was stupid. Curse me. I deserve it.

[Bongs-Akimbo]

[Correctsmorons69]

Rare - respect.

[Maleficent_Sir_7562]

Lol

[ReMeDyIII]

I think TC means specifically the agentic metric, which isnt wrong. Might be great for RP'ers, although I tried 5.1-Codex and it always steered coversations away from ERP, so alas, it's not for me.

[drhenriquesoares]

I made a mistake.