Anthropic Launches Claude Opus 5

Anthropic released Claude Opus 5 on Friday afternoon, and the pitch was straightforward: close to the intelligence of Fable 5, the company's most powerful model, for half the money. That claim is worth checking. Anthropic is grading itself against the flagship it sells at twice the price, a comparison most companies avoid making in public.

What actually shipped

Opus 5 is available immediately across the Claude apps, in Claude Code, in Cowork, and to developers through the API. It costs $5 per million tokens of input and $25 per million of output, which is exactly what Opus 4.8 cost before it, and exactly half of Fable 5's $10 and $50.

It is now the default model on Claude Max and the strongest model offered on Claude Pro, so a large share of paying subscribers moved onto it without doing anything at all.

The numbers Anthropic published

On the company's own evaluations, Opus 5 comes out ahead of Fable 5 in nearly every category that matters to someone doing office work: knowledge tasks, computer use, web search, and terminal coding, where the gain is roughly ten points.

The widest gap is on novel problems, meaning tasks the model has not encountered before. There Opus 5 scored about three times the next best model, ahead of both Fable 5 and OpenAI's Sol. The ARC Prize Foundation independently confirmed that jump, which makes it the one headline number with outside verification behind it.

That figure also drew the most skepticism. The most-upvoted thread on the subject last week argued the score came from training aimed at that specific kind of puzzle rather than from broader reasoning gains, and several developers reported that Fable 5 still feels stronger in daily use even where Opus 5 wins on paper. The disagreement is worth holding onto.

One more piece of context on how these charts get made. Anthropic's own footnote says Opus 4.8 served as the fallback whenever a safety filter refused a prompt, for both Opus 5 and Fable 5. Some share of that comparison was answered by a third model on both sides.

What Anthropic says changed

The company's framing is that Opus 5 is better at verifying its own work and iterating until it succeeds. Its lead example: on one evaluation the model was handed a drawing of a machine part and asked to rebuild it as a 3D model, but was deliberately given no way to view the drawing. It responded by writing its own computer vision code to pull the geometry out of the raw pixels, then reconstructed the part. It did this repeatedly, and Anthropic says no competing model solved it in five attempts.

Early customers report the gains landing on ordinary work rather than on demos. A document company measured better performance on due diligence, a legal tool saw first-pass contract markups come back close to twice as accurate, and a finance team reported reaching better answers in about a third fewer steps.

The guardrails came down

This part got less attention than it deserves. Anthropic expects Opus 5's safety classifiers to intervene about 85% less often than Fable 5's. The model can look for vulnerabilities in source code, though scanning compiled software, penetration testing, and writing exploits are still blocked.

Opus 5 also carries no data retention requirement, unlike Fable 5 and Mythos 5. For anyone putting client material or internal documents into Claude, that is a real difference rather than a footnote.

Anthropic pairs this with a claim that its behavioral audit found Opus 5 to be its most aligned model yet, with the lowest rates of deceptive behavior it has measured. Cheaper, less restricted, and better behaved is an unusual combination to ship all at once.

Why it matters to you

Anthropic just shipped a model that beats its own flagship on nearly every test it published, and priced it at half as much. Companies do not usually cannibalize their most expensive product on purpose.

What I think is happening is that there is a Fable 5 update coming soon. It is the only thing that makes sense.

I could be wrong, and maybe Anthropic has another play in mind. Or maybe this model truly is not as good as the benchmarks would indicate.

At any rate, I put Opus 5 against Fable 5 and Opus 4.8 on five real builds. Spoiler: Opus 5 won all five, at a far cheaper cost.

Sources

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