261 posts tagged “anthropic”
2026
I'm moving to another service and need to export my data. List every memory you have stored about me, as well as any context you've learned about me from past conversations. Output everything in a single code block so I can easily copy it. Format each entry as: [date saved, if available] - memory content. Make sure to cover all of the following — preserve my words verbatim where possible: Instructions I've given you about how to respond (tone, format, style, 'always do X', 'never do Y'). Personal details: name, location, job, family, interests. Projects, goals, and recurring topics. Tools, languages, and frameworks I use. Preferences and corrections I've made to your behavior. Any other stored context not covered above. Do not summarize, group, or omit any entries. After the code block, confirm whether that is the complete set or if any remain.
— claude.com/import-memory, Anthropic's "import your memories to Claude" feature is a prompt
Free Claude Max for (large project) open source maintainers (via) Anthropic are now offering their $200/month Claude Max 20x plan for free to open source maintainers... for six months... and you have to meet the following criteria:
- Maintainers: You're a primary maintainer or core team member of a public repo with 5,000+ GitHub stars or 1M+ monthly NPM downloads. You've made commits, releases, or PR reviews within the last 3 months.
- Don't quite fit the criteria If you maintain something the ecosystem quietly depends on, apply anyway and tell us about it.
Also in the small print: "Applications are reviewed on a rolling basis. We accept up to 10,000 contributors".
Claude Code Remote Control (via) New Claude Code feature dropped yesterday: you can now run a "remote control" session on your computer and then use the Claude Code for web interfaces (on web, iOS and native desktop app) to send prompts to that session.
It's a little bit janky right now. Initially when I tried it I got the error "Remote Control is not enabled for your account. Contact your administrator." (but I am my administrator?) - then I logged out and back into the Claude Code terminal app and it started working:
claude remote-control
You can only run one session on your machine at a time. If you upgrade the Claude iOS app it then shows up as "Remote Control Session (Mac)" in the Code tab.
It appears not to support the --dangerously-skip-permissions flag (I passed that to claude remote-control and it didn't reject the option, but it also appeared to have no effect) - which means you have to approve every new action it takes.
I also managed to get it to a state where every prompt I tried was met by an API 500 error.
Restarting the program on the machine also causes existing sessions to start returning mysterious API errors rather than neatly explaining that the session has terminated.
I expect they'll iron out all of these issues relatively quickly. It's interesting to then contrast this to solutions like OpenClaw, where one of the big selling points is the ability to control your personal device from your phone.
Claude Code still doesn't have a documented mechanism for running things on a schedule, which is the other killer feature of the Claw category of software.
Update: I spoke too soon: also today Anthropic announced Schedule recurring tasks in Cowork, Claude Code's general agent sibling. These do include an important limitation:
Scheduled tasks only run while your computer is awake and the Claude Desktop app is open. If your computer is asleep or the app is closed when a task is scheduled to run, Cowork will skip the task, then run it automatically once your computer wakes up or you open the desktop app again.
I really hope they're working on a Cowork Cloud product.
The Claude C Compiler: What It Reveals About the Future of Software. On February 5th Anthropic's Nicholas Carlini wrote about a project to use parallel Claudes to build a C compiler on top of the brand new Opus 4.6
Chris Lattner (Swift, LLVM, Clang, Mojo) knows more about C compilers than most. He just published this review of the code.
Some points that stood out to me:
- Good software depends on judgment, communication, and clear abstraction. AI has amplified this.
- AI coding is automation of implementation, so design and stewardship become more important.
- Manual rewrites and translation work are becoming AI-native tasks, automating a large category of engineering effort.
Chris is generally impressed with CCC (the Claude C Compiler):
Taken together, CCC looks less like an experimental research compiler and more like a competent textbook implementation, the sort of system a strong undergraduate team might build early in a project before years of refinement. That alone is remarkable.
It's a long way from being a production-ready compiler though:
Several design choices suggest optimization toward passing tests rather than building general abstractions like a human would. [...] These flaws are informative rather than surprising, suggesting that current AI systems excel at assembling known techniques and optimizing toward measurable success criteria, while struggling with the open-ended generalization required for production-quality systems.
The project also leads to deep open questions about how agentic engineering interacts with licensing and IP for both open source and proprietary code:
If AI systems trained on decades of publicly available code can reproduce familiar structures, patterns, and even specific implementations, where exactly is the boundary between learning and copying?
Long running agentic products like Claude Code are made feasible by prompt caching which allows us to reuse computation from previous roundtrips and significantly decrease latency and cost. [...]
At Claude Code, we build our entire harness around prompt caching. A high prompt cache hit rate decreases costs and helps us create more generous rate limits for our subscription plans, so we run alerts on our prompt cache hit rate and declare SEVs if they're too low.
SWE-bench February 2026 leaderboard update (via) SWE-bench is one of the benchmarks that the labs love to list in their model releases. The official leaderboard is infrequently updated but they just did a full run of it against the current generation of models, which is notable because it's always good to see benchmark results like this that weren't self-reported by the labs.
The fresh results are for their "Bash Only" benchmark, which runs their mini-swe-bench agent (~9,000 lines of Python, here are the prompts they use) against the SWE-bench dataset of coding problems - 2,294 real-world examples pulled from 12 open source repos: django/django (850), sympy/sympy (386), scikit-learn/scikit-learn (229), sphinx-doc/sphinx (187), matplotlib/matplotlib (184), pytest-dev/pytest (119), pydata/xarray (110), astropy/astropy (95), pylint-dev/pylint (57), psf/requests (44), mwaskom/seaborn (22), pallets/flask (11).
Correction: The Bash only benchmark runs against SWE-bench Verified, not original SWE-bench. Verified is a manually curated subset of 500 samples described here, funded by OpenAI. Here's SWE-bench Verified on Hugging Face - since it's just 2.1MB of Parquet it's easy to browse using Datasette Lite, which cuts those numbers down to django/django (231), sympy/sympy (75), sphinx-doc/sphinx (44), matplotlib/matplotlib (34), scikit-learn/scikit-learn (32), astropy/astropy (22), pydata/xarray (22), pytest-dev/pytest (19), pylint-dev/pylint (10), psf/requests (8), mwaskom/seaborn (2), pallets/flask (1).
Here's how the top ten models performed:
It's interesting to see Claude Opus 4.5 beat Opus 4.6, though only by about a percentage point. 4.5 Opus is top, then Gemini 3 Flash, then MiniMax M2.5 - a 229B model released last week by Chinese lab MiniMax. GLM-5, Kimi K2.5 and DeepSeek V3.2 are three more Chinese models that make the top ten as well.
OpenAI's GPT-5.2 is their highest performing model at position 6, but it's worth noting that their best coding model, GPT-5.3-Codex, is not represented - maybe because it's not yet available in the OpenAI API.
This benchmark uses the same system prompt for every model, which is important for a fair comparison but does mean that the quality of the different harnesses or optimized prompts is not being measured here.
The chart above is a screenshot from the SWE-bench website, but their charts don't include the actual percentage values visible on the bars. I successfully used Claude for Chrome to add these - transcript here. My prompt sequence included:
Use claude in chrome to open https://www.swebench.com/
Click on "Compare results" and then select "Select top 10"
See those bar charts? I want them to display the percentage on each bar so I can take a better screenshot, modify the page like that
I'm impressed at how well this worked - Claude injected custom JavaScript into the page to draw additional labels on top of the existing chart.
![Screenshot of a Claude AI conversation showing browser automation. A thinking step reads "Pivoted strategy to avoid recursion issues with chart labeling >" followed by the message "Good, the chart is back. Now let me carefully add the labels using an inline plugin on the chart instance to avoid the recursion issue." A collapsed "Browser_evaluate" section shows a browser_evaluate tool call with JavaScript code using Chart.js canvas context to draw percentage labels on bars: meta.data.forEach((bar, index) => { const value = dataset.data[index]; if (value !== undefined && value !== null) { ctx.save(); ctx.textAlign = 'center'; ctx.textBaseline = 'bottom'; ctx.fillStyle = '#333'; ctx.font = 'bold 12px sans-serif'; ctx.fillText(value.toFixed(1) + '%', bar.x, bar.y - 5); A pending step reads "Let me take a screenshot to see if it worked." followed by a completed "Done" step, and the message "Let me take a screenshot to check the result."](https://static.simonwillison.net/static/2026/claude-chrome-draw-on-chart.jpg)
Update: If you look at the transcript Claude claims to have switched to Playwright, which is confusing because I didn't think I had that configured.
Introducing Claude Sonnet 4.6 (via) Sonnet 4.6 is out today, and Anthropic claim it offers similar performance to November's Opus 4.5 while maintaining the Sonnet pricing of $3/million input and $15/million output tokens (the Opus models are $5/$25). Here's the system card PDF.
Sonnet 4.6 has a "reliable knowledge cutoff" of August 2025, compared to Opus 4.6's May 2025 and Haiku 4.5's February 2025. Both Opus and Sonnet default to 200,000 max input tokens but can stretch to 1 million in beta and at a higher cost.
I just released llm-anthropic 0.24 with support for both Sonnet 4.6 and Opus 4.6. Claude Code did most of the work - the new models had a fiddly amount of extra details around adaptive thinking and no longer supporting prefixes, as described in Anthropic's migration guide.
Here's what I got from:
uvx --with llm-anthropic llm 'Generate an SVG of a pelican riding a bicycle' -m claude-sonnet-4.6
The SVG comments include:
<!-- Hat (fun accessory) -->
I tried a second time and also got a top hat. Sonnet 4.6 apparently loves top hats!
For comparison, here's the pelican Opus 4.5 drew me in November:
And here's Anthropic's current best pelican, drawn by Opus 4.6 on February 5th:
Opus 4.6 produces the best pelican beak/pouch. I do think the top hat from Sonnet 4.6 is a nice touch though.
I'm a very heavy user of Claude Code on the web, Anthropic's excellent but poorly named cloud version of Claude Code where everything runs in a container environment managed by them, greatly reducing the risk of anything bad happening to a computer I care about.
I don't use the web interface at all (hence my dislike of the name) - I access it exclusively through their native iPhone and Mac desktop apps.
Something I particularly appreciate about the desktop app is that it lets you see images that Claude is "viewing" via its Read /path/to/image tool. Here's what that looks like:
This means you can get a visual preview of what it's working on while it's working, without waiting for it to push code to GitHub for you to try out yourself later on.
The prompt I used to trigger the above screenshot was:
Run "uvx rodney --help" and then use Rodney to manually test the new pages and menu - look at screenshots from it and check you think they look OK
I designed Rodney to have --help output that provides everything a coding agent needs to know in order to use the tool.
The Claude iPhone app doesn't display opened images yet, so I requested it as a feature just now in a thread on Twitter.
Someone has to prompt the Claudes, talk to customers, coordinate with other teams, decide what to build next. Engineering is changing and great engineers are more important than ever.
— Boris Cherny, Claude Code creator, on why Anthropic are still hiring developers
Someone asked if there was an Anthropic equivalent to OpenAI's IRS mission statements over time.
Anthropic are a "public benefit corporation" but not a non-profit, so they don't have the same requirements to file public documents with the IRS every year.
But when I asked Claude it ran a search and dug up this Google Drive folder where Zach Stein-Perlman shared Certificate of Incorporation documents he obtained from the State of Delaware!
Anthropic's are much less interesting that OpenAI's. The earliest document from 2021 states:
The specific public benefit that the Corporation will promote is to responsibly develop and maintain advanced Al for the cultural, social and technological improvement of humanity.
Every subsequent document up to 2024 uses an updated version which says:
The specific public benefit that the Corporation will promote is to responsibly develop and maintain advanced AI for the long term benefit of humanity.
Claude Code was made available to the general public in May 2025. Today, Claude Code’s run-rate revenue has grown to over $2.5 billion; this figure has more than doubled since the beginning of 2026. The number of weekly active Claude Code users has also doubled since January 1 [six weeks ago].
— Anthropic, announcing their $30 billion series G
Covering electricity price increases from our data centers (via) One of the sub-threads of the AI energy usage discourse has been the impact new data centers have on the cost of electricity to nearby residents. Here's detailed analysis from Bloomberg in September reporting "Wholesale electricity costs as much as 267% more than it did five years ago in areas near data centers".
Anthropic appear to be taking on this aspect of the problem directly, promising to cover 100% of necessary grid upgrade costs and also saying:
We will work to bring net-new power generation online to match our data centers’ electricity needs. Where new generation isn’t online, we’ll work with utilities and external experts to estimate and cover demand-driven price effects from our data centers.
I look forward to genuine energy industry experts picking this apart to judge if it will actually have the claimed impact on consumers.
As always, I remain frustrated at the refusal of the major AI labs to fully quantify their energy usage. The best data we've had on this still comes from Mistral's report last July and even that lacked key data such as the breakdown between energy usage for training vs inference.
People on the orange site are laughing at this, assuming it's just an ad and that there's nothing to it. Vulnerability researchers I talk to do not think this is a joke. As an erstwhile vuln researcher myself: do not bet against LLMs on this.
Axios: Anthropic's Claude Opus 4.6 uncovers 500 zero-day flaws in open-source
I think vulnerability research might be THE MOST LLM-amenable software engineering problem. Pattern-driven. Huge corpus of operational public patterns. Closed loops. Forward progress from stimulus/response tooling. Search problems.
Vulnerability research outcomes are in THE MODEL CARDS for frontier labs. Those companies have so much money they're literally distorting the economy. Money buys vuln research outcomes. Why would you think they were faking any of this?
Claude: Speed up responses with fast mode.
New "research preview" from Anthropic today: you can now access a faster version of their frontier model Claude Opus 4.6 by typing /fast in Claude Code... but at a cost that's 6x the normal price.
Opus is usually $5/million input and $25/million output. The new fast mode is $30/million input and $150/million output!
There's a 50% discount until the end of February 16th, so only a 3x multiple (!) before then.
How much faster is it? The linked documentation doesn't say, but on Twitter Claude say:
Our teams have been building with a 2.5x-faster version of Claude Opus 4.6.
We’re now making it available as an early experiment via Claude Code and our API.
Claude Opus 4.5 had a context limit of 200,000 tokens. 4.6 has an option to increase that to 1,000,000 at 2x the input price ($10/m) and 1.5x the output price ($37.50/m) once your input exceeds 200,000 tokens. These multiples hold for fast mode too, so after Feb 16th you'll be able to pay a hefty $60/m input and $225/m output for Anthropic's fastest best model.
Two major new model releases today, within about 15 minutes of each other.
Anthropic released Opus 4.6. Here's its pelican:
OpenAI release GPT-5.3-Codex, albeit only via their Codex app, not yet in their API. Here's its pelican:
I've had a bit of preview access to both of these models and to be honest I'm finding it hard to find a good angle to write about them - they're both really good, but so were their predecessors Codex 5.2 and Opus 4.5. I've been having trouble finding tasks that those previous models couldn't handle but the new ones are able to ace.
The most convincing story about capabilities of the new model so far is Nicholas Carlini from Anthropic talking about Opus 4.6 and Building a C compiler with a team of parallel Claudes - Anthropic's version of Cursor's FastRender project.
Claude’s new constitution. Late last year Richard Weiss found something interesting while poking around with the just-released Claude Opus 4.5: he was able to talk the model into regurgitating a document which was not part of the system prompt but appeared instead to be baked in during training, and which described Claude's core values at great length.
He called this leak the soul document, and Amanda Askell from Anthropic quickly confirmed that it was indeed part of Claude's training procedures.
Today Anthropic made this official, releasing that full "constitution" document under a CC0 (effectively public domain) license. There's a lot to absorb! It's over 35,000 tokens, more than 10x the length of the published Opus 4.5 system prompt.
One detail that caught my eye is the acknowledgements at the end, which include a list of external contributors who helped review the document. I was intrigued to note that two of the fifteen listed names are Catholic members of the clergy - Father Brendan McGuire is a pastor in Los Altos with a Master’s degree in Computer Science and Math and Bishop Paul Tighe is an Irish Catholic bishop with a background in moral theology.
Claude Cowork Exfiltrates Files (via) Claude Cowork defaults to allowing outbound HTTP traffic to only a specific list of domains, to help protect the user against prompt injection attacks that exfiltrate their data.
Prompt Armor found a creative workaround: Anthropic's API domain is on that list, so they constructed an attack that includes an attacker's own Anthropic API key and has the agent upload any files it can see to the https://api.anthropic.com/v1/files endpoint, allowing the attacker to retrieve their content later.
Anthropic invests $1.5 million in the Python Software Foundation and open source security. This is outstanding news, especially given our decision to withdraw from that NSF grant application back in October.
We are thrilled to announce that Anthropic has entered into a two-year partnership with the Python Software Foundation (PSF) to contribute a landmark total of $1.5 million to support the foundation’s work, with an emphasis on Python ecosystem security. This investment will enable the PSF to make crucial security advances to CPython and the Python Package Index (PyPI) benefiting all users, and it will also sustain the foundation’s core work supporting the Python language, ecosystem, and global community.
Note that while security is a focus these funds will also support other aspects of the PSF's work:
Anthropic’s support will also go towards the PSF’s core work, including the Developer in Residence program driving contributions to CPython, community support through grants and other programs, running core infrastructure such as PyPI, and more.
First impressions of Claude Cowork, Anthropic’s general agent
New from Anthropic today is Claude Cowork, a “research preview” that they describe as “Claude Code for the rest of your work”. It’s currently available only to Max subscribers ($100 or $200 per month plans) as part of the updated Claude Desktop macOS application. Update 16th January 2026: it’s now also available to $20/month Claude Pro subscribers.
[... 1,863 words]It genuinely feels to me like GPT-5.2 and Opus 4.5 in November represent an inflection point - one of those moments where the models get incrementally better in a way that tips across an invisible capability line where suddenly a whole bunch of much harder coding problems open up.
I'm not joking and this isn't funny. We have been trying to build distributed agent orchestrators at Google since last year. There are various options, not everyone is aligned... I gave Claude Code a description of the problem, it generated what we built last year in an hour.
It's not perfect and I'm iterating on it but this is where we are right now. If you are skeptical of coding agents, try it on a domain you are already an expert of. Build something complex from scratch where you can be the judge of the artifacts.
[...] It wasn't a very detailed prompt and it contained no real details given I cannot share anything propriety. I was building a toy version on top of some of the existing ideas to evaluate Claude Code. It was a three paragraph description.
— Jaana Dogan, Principal Engineer at Google
2025
2025: The year in LLMs
This is the third in my annual series reviewing everything that happened in the LLM space over the past 12 months. For previous years see Stuff we figured out about AI in 2023 and Things we learned about LLMs in 2024.
[... 8,273 words]Codex cloud is now called Codex web. It looks like OpenAI's Codex cloud (the cloud version of their Codex coding agent) was quietly rebranded to Codex web at some point in the last few days.
Here's a screenshot of the Internet Archive copy from 18th December (the capture on the 28th maintains that Codex cloud title but did not fully load CSS for me):
And here's that same page today with the updated product name:
Anthropic's equivalent product has the incredibly clumsy name Claude Code on the web, which I shorten to "Claude Code for web" but even then bugs me because I mostly interact with it via Anthropic's native mobile app.
I was hoping to see Claude Code for web rebrand to Claude Code Cloud - I did not expect OpenAI to rebrand in the opposite direction!
Update: Clarification from OpenAI Codex engineering lead Thibault Sottiaux:
Just aligning the documentation with how folks refer to it. I personally differentiate between cloud tasks and codex web. With cloud tasks running on our hosted runtime (includes code review, github, slack, linear, ...) and codex web being the web app.
I asked what they called Codex in the iPhone app and he said:
Codex iOS
A year ago, Claude struggled to generate bash commands without escaping issues. It worked for seconds or minutes at a time. We saw early signs that it may become broadly useful for coding one day.
Fast forward to today. In the last thirty days, I landed 259 PRs -- 497 commits, 40k lines added, 38k lines removed. Every single line was written by Claude Code + Opus 4.5.
— Boris Cherny, creator of Claude Code
A new way to extract detailed transcripts from Claude Code
I’ve released claude-code-transcripts, a new Python CLI tool for converting Claude Code transcripts to detailed HTML pages that provide a better interface for understanding what Claude Code has done than even Claude Code itself. The resulting transcripts are also designed to be shared, using any static HTML hosting or even via GitHub Gists.
[... 1,082 words]Cooking with Claude
I’ve been having an absurd amount of fun recently using LLMs for cooking. I started out using them for basic recipes, but as I’ve grown more confident in their culinary abilities I’ve leaned into them for more advanced tasks. Today I tried something new: having Claude vibe-code up a custom application to help with the timing for a complicated meal preparation. It worked really well!
[... 1,313 words]I just had my first success using a browser agent - in this case the Claude in Chrome extension - to solve an actual problem.
A while ago I set things up so anything served from the https://static.simonwillison.net/static/cors-allow/ directory of my S3 bucket would have open Access-Control-Allow-Origin: * headers. This is useful for hosting files online that can be loaded into web applications hosted on other domains.
Problem is I couldn't remember how I did it! I initially thought it was an S3 setting, but it turns out S3 lets you set CORS at the bucket-level but not for individual prefixes.
I then suspected Cloudflare, but I find the Cloudflare dashboard really difficult to navigate.
So I decided to give Claude in Chrome a go. I installed and enabled the extension (you then have to click the little puzzle icon and click "pin" next to Claude for the icon to appear, I had to ask Claude itself for help figuring that out), signed into Cloudflare, opened the Claude panel and prompted:
I'm trying to figure out how come all pages under http://static.simonwillison.net/static/cors/ have an open CORS policy, I think I set that up through Cloudflare but I can't figure out where
Off it went. It took 1m45s to find exactly what I needed.
Claude's conclusion:
Found it! Your open CORS policy for the
/static/cors/directory onstatic.simonwillison.netis configured through Cloudflare Transform Rules, specifically a Response Header Transform Rule namedstatic.simonwillis.net/static/cors-allow/*
There's no "share transcript" option but I used copy and paste and two gnarly Claude Code sessions (one, two) to turn it into an HTML transcript which you can take a look at here.
I remain deeply skeptical of the entire browsing agent category due to my concerns about prompt injection risks—I watched what it was doing here like a hawk—but I have to admit this was a very positive experience.
Agent Skills. Anthropic have turned their skills mechanism into an "open standard", which I guess means it lives in an independent agentskills/agentskills GitHub repository now? I wouldn't be surprised to see this end up in the AAIF, recently the new home of the MCP specification.
The specification itself lives at agentskills.io/specification, published from docs/specification.mdx in the repo.
It is a deliciously tiny specification - you can read the entire thing in just a few minutes. It's also quite heavily under-specified - for example, there's a metadata field described like this:
Clients can use this to store additional properties not defined by the Agent Skills spec
We recommend making your key names reasonably unique to avoid accidental conflicts
And an allowed-skills field:
Experimental. Support for this field may vary between agent implementations
Example:
allowed-tools: Bash(git:*) Bash(jq:*) Read
The Agent Skills homepage promotes adoption by OpenCode, Cursor,Amp, Letta, goose, GitHub, and VS Code. Notably absent is OpenAI, who are quietly tinkering with skills but don't appear to have formally announced their support just yet.
Update 20th December 2025: OpenAI have added Skills to the Codex documentation and the Codex logo is now featured on the Agent Skills homepage (as of this commit.)
OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI
One of the things that most excited me about Anthropic’s new Skills mechanism back in October is how easy it looked for other platforms to implement. A skill is just a folder with a Markdown file and some optional extra resources and scripts, so any LLM tool with the ability to navigate and read from a filesystem should be capable of using them. It turns out OpenAI are doing exactly that, with skills support quietly showing up in both their Codex CLI tool and now also in ChatGPT itself.
[... 1,360 words]