The interesting pattern with these Sonnet bumps: the practical gap between Sonnet and Opus keeps shrinking. At $3/15 per million tokens vs whatever Opus 4.6 costs, the question for most teams is no longer "which model is smarter" but "is the delta worth 10x the price."

For agent workloads specifically, consistency matters more than peak intelligence. A model that follows your system prompt correctly 98% of the time beats one that's occasionally brilliant but ignores instructions 5% of the time. The claim about improved instruction following is the most important line in the announcement if you're building on the API.

The computer use improvements are worth watching too. We're at the point where these models can reliably fill out a multi-step form or navigate between tabs. Not flashy, but that's the kind of boring automation that actually saves people time.

They're improved compared to 4.5 on my Extended NYT Connections benchmark (https://github.com/lechmazur/nyt-connections/).

Sonnet 4.6 Thinking 16K scores 57.6 on the Extended NYT Connections Benchmark. Sonnet 4.5 Thinking 16K scored 49.3.

Sonnet 4.6 No Reasoning scores 55.2. Sonnet 4.5 No Reasoning scored 47.4.

Enabling /extra-usage in my (personal) claude code[0] with this env:

    "ANTHROPIC_DEFAULT_SONNET_MODEL": "claude-sonnet-4-6[1m]"

has enabled the 1M context window.

Fixed a UI issue I had yesterday in a web app very effectively using claude in chrome. Definitely not the fastest model - but the breathing space of 1M context is great for browser use.

[0] Anthropic have given away a bunch of API credits to cc subscribers - you can claim them in your settings dashboard to use for this.

I'm a bit surprised it gets this question wrong (ChatGPT gets it right, even on instant). All the pre-reasoning models failed this question, but it's seemed solved since o1, and Sonnet 4.5 got it right.

https://claude.ai/share/876e160a-7483-4788-8112-0bb4490192af

This was sonnet 4.6 with extended thinking.

Waiting for the OpenAI GPT-5.3-mini release in 3..2..1

As with Opus 4.6, using the beta 1M context window incurs a 2x input cost and 1.5x output cost when going over >200K tokens: https://platform.claude.com/docs/en/about-claude/pricing

Opus 4.6 in Claude Code has been absolutely lousy with solving problems within its current context limit so if Sonnet 4.6 is able to do long-context problems (which would be roughly the same price of base Opus 4.6), then that may actually be a game changer.

The weirdest thing about this AI revolution is how smooth and continuous it is. If you look closely at differences between 4.6 and 4.5, it’s hard to see the subtle details.

A year ago today, Sonnet 3.5 (new), was the newest model. A week later, Sonnet 3.7 would be released.

Even 3.7 feels like ancient history! But in the gradient of 3.5 to 3.5 (new) to 3.7 to 4 to 4.1 to 4.5, I can’t think of one moment where I saw everything change. Even with all the noise in the headlines, it’s still been a silent revolution.

Am I just a believer in an emperor with no clothes? Or, somehow, against all probability and plausibility, are we all still early?

I can't wait for Haiku 4.6 ! the 4.5 is a beast for the right projects.

It's funny how they and OpenAI keep releasing these "minor" versions as if to imply their product was very stable and reliable at a major version and now they are just working through the backlog of smaller bugs and quirks, whereas - the tool is still fundamentally prone to the same class of errors it was three "major" versions ago. I guess that's what you get for not having a programmer at the helm (to borrow from Spolsky). Guys you are not releasing a 4.6 or a 5.3 anything - it's more likely you are still beta testing towards the 1.0.

It seems that extra-usage is required to use the 1M context window for Sonnet 4.6. This differs from Sonnet 4.5, which allows usage of the 1M context window with a Max plan.

```

/model claude-sonnet-4-6[1m]

⎿ API error: 429 {"type":"error","error": {"type":"rate_limit_error","message":"Extra usage is required for long context requests."},"request_id":"[redacted]"}

```