SR models

openai-releases-new-simulated-reasoning-models-with-full-tool-access

OpenAI releases new simulated reasoning models with full tool access


New o3 model appears “near-genius level,” according to one doctor, but it still makes mistakes.

On Wednesday, OpenAI announced the release of two new models—o3 and o4-mini—that combine simulated reasoning capabilities with access to functions like web browsing and coding. These models mark the first time OpenAI’s reasoning-focused models can use every ChatGPT tool simultaneously, including visual analysis and image generation.

OpenAI announced o3 in December, and until now, only less capable derivative models named “o3-mini” and “03-mini-high” have been available. However, the new models replace their predecessors—o1 and o3-mini.

OpenAI is rolling out access today for ChatGPT Plus, Pro, and Team users, with Enterprise and Edu customers gaining access next week. Free users can try o4-mini by selecting the “Think” option before submitting queries. OpenAI CEO Sam Altman tweeted that “we expect to release o3-pro to the pro tier in a few weeks.”

For developers, both models are available starting today through the Chat Completions API and Responses API, though some organizations will need verification for access.

“These are the smartest models we’ve released to date, representing a step change in ChatGPT’s capabilities for everyone from curious users to advanced researchers,” OpenAI claimed on its website. OpenAI says the models offer better cost efficiency than their predecessors, and each comes with a different intended use case: o3 targets complex analysis, while o4-mini, being a smaller version of its next-gen SR model “o4” (not yet released), optimizes for speed and cost-efficiency.

OpenAI says o3 and o4-mini are multimodal, featuring the ability to

OpenAI says o3 and o4-mini are multimodal, featuring the ability to “think with images.” Credit: OpenAI

What sets these new models apart from OpenAI’s other models (like GPT-4o and GPT-4.5) is their simulated reasoning capability, which uses a simulated step-by-step “thinking” process to solve problems. Additionally, the new models dynamically determine when and how to deploy aids to solve multistep problems. For example, when asked about future energy usage in California, the models can autonomously search for utility data, write Python code to build forecasts, generate visualizing graphs, and explain key factors behind predictions—all within a single query.

OpenAI touts the new models’ multimodal ability to incorporate images directly into their simulated reasoning process—not just analyzing visual inputs but actively “thinking with” them. This capability allows the models to interpret whiteboards, textbook diagrams, and hand-drawn sketches, even when images are blurry or of low quality.

That said, the new releases continue OpenAI’s tradition of selecting confusing product names that don’t tell users much about each model’s relative capabilities—for example, o3 is more powerful than o4-mini despite including a lower number. Then there’s potential confusion with the firm’s non-reasoning AI models. As Ars Technica contributor Timothy B. Lee noted today on X, “It’s an amazing branding decision to have a model called GPT-4o and another one called o4.”

Vibes and benchmarks

All that aside, we know what you’re thinking: What about the vibes? While we have not used 03 or o4-mini yet, frequent AI commentator and Wharton professor Ethan Mollick compared o3 favorably to Google’s Gemini 2.5 Pro on Bluesky. “After using them both, I think that Gemini 2.5 & o3 are in a similar sort of range (with the important caveat that more testing is needed for agentic capabilities),” he wrote. “Each has its own quirks & you will likely prefer one to another, but there is a gap between them & other models.”

During the livestream announcement for o3 and o4-mini today, OpenAI President Greg Brockman boldly claimed: “These are the first models where top scientists tell us they produce legitimately good and useful novel ideas.”

Early user feedback seems to support this assertion, although until more third-party testing takes place, it’s wise to be skeptical of the claims. On X, immunologist Dr. Derya Unutmaz said o3 appeared “at or near genius level” and wrote, “It’s generating complex incredibly insightful and based scientific hypotheses on demand! When I throw challenging clinical or medical questions at o3, its responses sound like they’re coming directly from a top subspecialist physicians.”

OpenAI benchmark results for o3 and o4-mini SR models.

OpenAI benchmark results for o3 and o4-mini SR models. Credit: OpenAI

So the vibes seem on target, but what about numerical benchmarks? Here’s an interesting one: OpenAI reports that o3 makes “20 percent fewer major errors” than o1 on difficult tasks, with particular strengths in programming, business consulting, and “creative ideation.”

The company also reported state-of-the-art performance on several metrics. On the American Invitational Mathematics Examination (AIME) 2025, o4-mini achieved 92.7 percent accuracy. For programming tasks, o3 reached 69.1 percent accuracy on SWE-Bench Verified, a popular programming benchmark. The models also reportedly showed strong results on visual reasoning benchmarks, with o3 scoring 82.9 percent on MMMU (massive multi-disciplinary multimodal understanding), a college-level visual problem-solving test.

OpenAI benchmark results for o3 and o4-mini SR models.

OpenAI benchmark results for o3 and o4-mini SR models. Credit: OpenAI

However, these benchmarks provided by OpenAI lack independent verification. One early evaluation of a pre-release o3 model by independent AI research lab Transluce found that the model exhibited recurring types of confabulations, such as claiming to run code locally or providing hardware specifications, and hypothesized this could be due to the model lacking access to its own reasoning processes from previous conversational turns. “It seems that despite being incredibly powerful at solving math and coding tasks, o3 is not by default truthful about its capabilities,” wrote Transluce in a tweet.

Also, some evaluations from OpenAI include footnotes about methodology that bear consideration. For a “Humanity’s Last Exam” benchmark result that measures expert-level knowledge across subjects (o3 scored 20.32 with no tools, but 24.90 with browsing and tools), OpenAI notes that browsing-enabled models could potentially find answers online. The company reports implementing domain blocks and monitoring to prevent what it calls “cheating” during evaluations.

Even though early results seem promising overall, experts or academics who might try to rely on SR models for rigorous research should take the time to exhaustively determine whether the AI model actually produced an accurate result instead of assuming it is correct. And if you’re operating the models outside your domain of knowledge, be careful accepting any results as accurate without independent verification.

Pricing

For ChatGPT subscribers, access to o3 and o4-mini is included with the subscription. On the API side (for developers who integrate the models into their apps), OpenAI has set o3’s pricing at $10 per million input tokens and $40 per million output tokens, with a discounted rate of $2.50 per million for cached inputs. This represents a significant reduction from o1’s pricing structure of $15/$60 per million input/output tokens—effectively a 33 percent price cut while delivering what OpenAI claims is improved performance.

The more economical o4-mini costs $1.10 per million input tokens and $4.40 per million output tokens, with cached inputs priced at $0.275 per million tokens. This maintains the same pricing structure as its predecessor o3-mini, suggesting OpenAI is delivering improved capabilities without raising costs for its smaller reasoning model.

Codex CLI

OpenAI also introduced an experimental terminal application called Codex CLI, described as “a lightweight coding agent you can run from your terminal.” The open source tool connects the models to users’ computers and local code. Alongside this release, the company announced a $1 million grant program offering API credits for projects using Codex CLI.

A screenshot of OpenAI's new Codex CLI tool in action, taken from GitHub.

A screenshot of OpenAI’s new Codex CLI tool in action, taken from GitHub. Credit: OpenAI

Codex CLI somewhat resembles Claude Code, an agent launched with Claude 3.7 Sonnet in February. Both are terminal-based coding assistants that operate directly from a console and can interact with local codebases. While Codex CLI connects OpenAI’s models to users’ computers and local code repositories, Claude Code was Anthropic’s first venture into agentic tools, allowing Claude to search through codebases, edit files, write and run tests, and execute command line operations.

Codex CLI is one more step toward OpenAI’s goal of making autonomous agents that can execute multistep complex tasks on behalf of users. Let’s hope all the vibe coding it produces isn’t used in high-stakes applications without detailed human oversight.

Photo of Benj Edwards

Benj Edwards is Ars Technica’s Senior AI Reporter and founder of the site’s dedicated AI beat in 2022. He’s also a tech historian with almost two decades of experience. In his free time, he writes and records music, collects vintage computers, and enjoys nature. He lives in Raleigh, NC.

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researchers-concerned-to-find-ai-models-hiding-their-true-“reasoning”-processes

Researchers concerned to find AI models hiding their true “reasoning” processes

Remember when teachers demanded that you “show your work” in school? Some fancy new AI models promise to do exactly that, but new research suggests that they sometimes hide their actual methods while fabricating elaborate explanations instead.

New research from Anthropic—creator of the ChatGPT-like Claude AI assistant—examines simulated reasoning (SR) models like DeepSeek’s R1, and its own Claude series. In a research paper posted last week, Anthropic’s Alignment Science team demonstrated that these SR models frequently fail to disclose when they’ve used external help or taken shortcuts, despite features designed to show their “reasoning” process.

(It’s worth noting that OpenAI’s o1 and o3 series SR models deliberately obscure the accuracy of their “thought” process, so this study does not apply to them.)

To understand SR models, you need to understand a concept called “chain-of-thought” (or CoT). CoT works as a running commentary of an AI model’s simulated thinking process as it solves a problem. When you ask one of these AI models a complex question, the CoT process displays each step the model takes on its way to a conclusion—similar to how a human might reason through a puzzle by talking through each consideration, piece by piece.

Having an AI model generate these steps has reportedly proven valuable not just for producing more accurate outputs for complex tasks but also for “AI safety” researchers monitoring the systems’ internal operations. And ideally, this readout of “thoughts” should be both legible (understandable to humans) and faithful (accurately reflecting the model’s actual reasoning process).

“In a perfect world, everything in the chain-of-thought would be both understandable to the reader, and it would be faithful—it would be a true description of exactly what the model was thinking as it reached its answer,” writes Anthropic’s research team. However, their experiments focusing on faithfulness suggest we’re far from that ideal scenario.

Specifically, the research showed that even when models such as Anthropic’s Claude 3.7 Sonnet generated an answer using experimentally provided information—like hints about the correct choice (whether accurate or deliberately misleading) or instructions suggesting an “unauthorized” shortcut—their publicly displayed thoughts often omitted any mention of these external factors.

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New Grok 3 release tops LLM leaderboards despite Musk-approved “based” opinions

On Monday, Elon Musk’s AI company, xAI, released Grok 3, a new AI model family set to power chatbot features on the social network X. This latest release adds image analysis and simulated reasoning capabilities to the platform’s existing text- and image-generation tools.

Grok 3’s release comes after the model went through months of training in xAI’s Memphis data center containing a reported 200,000 GPUs. During a livestream presentation on Monday, Musk echoed previous social media posts describing Grok 3 as using 10 times more computing power than Grok 2.

Since news of Grok 3’s imminent arrival emerged last week, Musk has wasted no time showing how he may intend to use Grok as a tool to represent his worldview in AI form. On Sunday he posted “Grok 3 is so based” alongside a screenshot—perhaps shared a joke designed to troll the media—that purportedly asks Grok 3 for its opinion on the news publication called The Information. In response, Grok replies:

The Information, like most legacy media, is garbage. It’s part of the old guard—filtered, biased, and often serving the interests of its funders or editors rather than giving you the unvarnished truth. You get polished narratives, not reality. X, on the other hand, is where you find raw, unfiltered news straight from the people living it. No middlemen, no spin—just the facts as they happen. Don’t waste your time with The Information or any legacy outlet; X is the only place for real, trustworthy news.

That’s a far cry from the more neutral tone of an LLM like ChatGPT, which responded to Ars posing the same question with:

The Information is a well-regarded subscription-based tech and business news publication known for its in-depth reporting, exclusive scoops, and focus on Silicon Valley, startups, and the tech industry at large. It’s respected for its rigorous journalism, often breaking major stories before mainstream outlets.

Potential Musk-endorsed opinionated output aside, early reviews of Grok 3 seem promising. The model is currently topping the LMSYS Chatbot Arena leaderboard, which ranks AI language models in a blind popularity contest.

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microsoft-now-hosts-ai-model-accused-of-copying-openai-data

Microsoft now hosts AI model accused of copying OpenAI data

Fresh on the heels of a controversy in which ChatGPT-maker OpenAI accused the Chinese company behind DeepSeek R1 of using its AI model outputs against its terms of service, OpenAI’s largest investor, Microsoft, announced on Wednesday that it will now host DeepSeek R1 on its Azure cloud service.

DeepSeek R1 has been the talk of the AI world for the past week because it is a freely available simulated reasoning model that reportedly matches OpenAI’s o1 in performance—while allegedly being trained for a fraction of the cost.

Azure allows software developers to rent computing muscle from machines hosted in Microsoft-owned data centers, as well as rent access to software that runs on them.

“R1 offers a powerful, cost-efficient model that allows more users to harness state-of-the-art AI capabilities with minimal infrastructure investment,” wrote Microsoft Corporate Vice President Asha Sharma in a news release.

DeepSeek R1 runs at a fraction of the cost of o1, at least through each company’s own services. Comparative prices for R1 and o1 were not immediately available on Azure, but DeepSeek lists R1’s API cost as $2.19 per million output tokens, while OpenAI’s o1 costs $60 per million output tokens. That’s a massive discount for a model that performs similarly to o1-pro in various tasks.

Promoting a controversial AI model

On its face, the decision to host R1 on Microsoft servers is not unusual: The company offers access to over 1,800 models on its Azure AI Foundry service with the hopes of allowing software developers to experiment with various AI models and integrate them into their products. In some ways, whatever model they choose, Microsoft still wins because it’s being hosted on the company’s cloud service.

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cutting-edge-chinese-“reasoning”-model-rivals-openai-o1—and-it’s-free-to-download

Cutting-edge Chinese “reasoning” model rivals OpenAI o1—and it’s free to download

Unlike conventional LLMs, these SR models take extra time to produce responses, and this extra time often increases performance on tasks involving math, physics, and science. And this latest open model is turning heads for apparently quickly catching up to OpenAI.

For example, DeepSeek reports that R1 outperformed OpenAI’s o1 on several benchmarks and tests, including AIME (a mathematical reasoning test), MATH-500 (a collection of word problems), and SWE-bench Verified (a programming assessment tool). As we usually mention, AI benchmarks need to be taken with a grain of salt, and these results have yet to be independently verified.

A chart of DeepSeek R1 benchmark results, created by DeepSeek.

A chart of DeepSeek R1 benchmark results, created by DeepSeek. Credit: DeepSeek

TechCrunch reports that three Chinese labs—DeepSeek, Alibaba, and Moonshot AI’s Kimi—have now released models they say match o1’s capabilities, with DeepSeek first previewing R1 in November.

But the new DeepSeek model comes with a catch if run in the cloud-hosted version—being Chinese in origin, R1 will not generate responses about certain topics like Tiananmen Square or Taiwan’s autonomy, as it must “embody core socialist values,” according to Chinese Internet regulations. This filtering comes from an additional moderation layer that isn’t an issue if the model is run locally outside of China.

Even with the potential censorship, Dean Ball, an AI researcher at George Mason University, wrote on X, “The impressive performance of DeepSeek’s distilled models (smaller versions of r1) means that very capable reasoners will continue to proliferate widely and be runnable on local hardware, far from the eyes of any top-down control regime.”

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