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Okay, I've *finally* sent out a newsletter.
I'm trying out Substack. Let's see if it works.
In this one:
- Personal updates
- A theory of 3 constraints in tech services
- Medi-Cal friction mapping
daveguarino.substack.com/p/d…
Dave Guarino retweeted
Mike was my colleague at Berkeley, and he's been fairly skeptical of deep learning's trajectory for years. Most scientists are skeptics, and it can take a big shock to get someone to consider a possibility that goes against the anchoring effect coded in our DNA.
I too was somewhat of a skeptic until ~6 months ago, and people ask me all the time why I joined Anthropic.
It started in April, when a friend I've known for 20 yrs messaged me saying he'd be in the Bay Area in a week, and he suggested we meet up. I invited him to my house for dinner, and he told me he had just joined Anthropic. He said the models were becoming increasingly more capable, and he believed both that they'd soon be smarter than him and also that all intellectual work would be highly devalued in the near future, and lastly that society was not at all ready for what's coming.
I'd of course heard claims similar to this before, but not from a friend I'd known for this long, and who I trusted, at my dining room table. It was the initial shock needed to destabilize my own anchoring. Also, I've been fortunate to work with and/or mentor many smart people in my life (e.g. Fields medalists, a 4x Putnam Fellow, IOI first place winners, etc.), so I feel pretty calibrated in recognizing very smart people, and this was someone who is definitely very smart and with impressive such credentials. So, it was hard to ignore this friend saying the models would be smarter than even him in particular.
After that dinner, I decided to do an informal survey, calling and meeting up with a lot of my friends who now work on improving model capabilities at these frontier labs. They all agreed with that first friend. These were all people I'd known 10, 15, 20 years, who mentored me, or I mentored them, or we met professionally in academia. These are people I trust, and their beliefs on this topic were consistent.
I then spent a whole lot of time understanding the missions of different companies, and talking to current and former employees and people in leadership. I read Dario's (long) essays and watched videos on YouTube of company leaders being interviewed. Anthropic's stated mission "to ensure that the world safely makes the transition through transformative AI" felt like exactly the right guiding principle to handle such a society-disrupting technology, and everyone I spoke to at the company was very aligned with this mission. It's easily the most mission-focused place I've ever been at, and everyone takes the work extremely seriously and with a profound sense of responsibility.
And now here I am. And being on the inside, the pace of progress has surprised me more than I first imagined. The moment that pure mathematicians are in, to me, is just a microcosm of what I predict a much larger of society will be grappling with in the not too distant future, and I really hope our leaders and the general public internalize sooner than later just how significant a moment we're in.
Michael Jordan (the machine learning one): "Superintelligence is Science Fiction" 🔥🔥🔥
di.ens.fr/~fbach/MJordan_ITW…
Dave Guarino retweeted
Opus 5.5 is way, way, way better than Opus 5. Sorry about that model, please try this one.
Dave Guarino retweeted
We Must Pace the Frontier: I’ve written a new essay on why the AI industry should slow down, with a three-part plan for doing so.
Anthropic is unilaterally committing to the first of these steps. We’ll provide third-party evaluators with permanent, employee-level access to our systems, so that they can verify adherence to our safety measures, report on incidents, and assess models’ alignment during training.
You can read the full post here: darioamodei.com/post/we-must…
Dave Guarino retweeted
Fun activity when waiting in line for something: ask AI to explain the unit economics of the store you’re at
Dave Guarino retweeted
We’ve received notice that the Department of Commerce has lifted export controls on Claude Fable 5 and Mythos 5.
We'll begin restoring access tomorrow, and will share an update soon.
We’re grateful to our users for their patience, and to everyone who worked with us on redeploying the models.
Dave Guarino retweeted
🧵Claude Tag without the Tag (aka Ambient Claude)
One of my favorite ways to use Claude Tag is as an ambient partner -- one you don't need to explicitly tag.
How to get this set up?
Dave Guarino retweeted
Today I'm publishing a new essay, Policy on the AI Exponential. AI is progressing extremely fast—much faster than the policy process was built to handle. The essay lays out where I think the technology is now, and the action needed to close the gap: darioamodei.com/post/policy-…
Dave Guarino retweeted
Today, we're introducing Claude Fable 5 and Mythos 5, two configurations of our next major language model.
I'd normally highlight the numbers: It's SOTA on nearly all benchmarks. I want to talk about something else, because with Fable 5 out in the world, I think a third era quietly started today.
I lead Claude Code & Cowork on the desktop, so I think a lot about how people use AI to get work done. I believe we're about to see a major shift, moving from giving AI tasks to giving it responsibilities.
Dave Guarino retweeted
Within ~2 years, there might be >0.5 Manhattan Projects worth of philanthropic $$$ to spend on the biggest challenges, like cyber or biodefense.
@nanransohoff is right: the hard part is finding enough good organizations to spend the $.
You should build one!
New blog post: The third wave of American philanthropy
Hundreds of billions of dollars in new philanthropic capital will soon become liquid. The OpenAI Foundation holds 26% of OpenAI, worth about $220B at today’s valuation. Anthropic’s seven co-founders have pledged to give away 80% of their wealth and have instituted the most aggressive donor matching program for employees in tech history.
How much does this all add up to? And how meaningful is that in the context of philanthropy today?
I was doing some simple napkin math to wrap my head around the scale of what’s coming, and radicalized myself in the process. I had dramatically underappreciated the scale of the philanthropic capital that’s about to become available and the corresponding gap in talent and organizations that will be needed to make the most of it.
This piece aims to directionally sketch the scale of what’s coming, the gap in operational capacity needed to absorb it, and what we can do to fill it.
(Link to full post in reply)
We are constrained first by what we believe to be possible, and then, only subsequently, by what is in fact possible.
(And as the latter changes we really, really need to update the former quickly.)
Dave Guarino retweeted
Head of Frontier Red-Team at Anthropic.
xitter.cf/i/status/2054613618168…
A lot of people have been wondering about Mythos, Glasswing, and the vulns we / our partners are fixing. Today, I’m excited for us to start sharing more. (For context, I lead Glasswing @AnthropicAI.)
Two independent evaluations this week—from XBOW and the UK AISI—confirm what we've been seeing internally: Claude Mythos Preview is a step change in autonomous cybersecurity capabilities. We need to start preparing fast for a world of models with this level of capabilities.
The UK AI Security Institute tested the model we shipped at the launch of Project Glasswing and found Mythos Preview is the first model to solve both of their end-to-end cyber ranges, including one (Cooling Tower) which no model had ever cleared. But attackers (and defenders) have sophistication & cost constraints – Mythos is also the only model that clears every one of their tasks estimated over 8 hours under their deliberately low 2.5M-token cap.
XBOW tested it on their offensive security benchmarks, finding "token-for-token, unprecedented precision." It's the only model to succeed at subtle V8 sandbox work.
Other Glasswing partners shared similar stories. In a few weeks of testing, Mythos Preview has helped them find many thousands of (estimated) high + critical severity vulnerabilities, sometimes double what they'd normally find in a year.
I don't share this to boost Mythos. In fact, this is not about Mythos. It’s about preparing for the coming world of models being better, faster, cheaper, and more creative than some of the best human experts at dual use capabilities. Clearly, we need them supporting defenders as widely as can be done safely – and especially the least resourced ones.
Within a year, Mythos will probably look quite dumb (relative to other new models). And others may release openly available or unguardrailed models of Mythos-level capabilities.
We started Project Glasswing because capabilities like Mythos Preview's won't stay rare, or stay in careful hands. We are bringing it to defenders as fast as we responsibly can, while working to figure out, for example, the right safeguards and patching & disclosure processes.
Also, to be clear, compute has never been a limiter in our rollout.
Expect a fuller update on our Glasswing work in the coming days.
XBOW report: xbow.com/blog/mythos-offensi…
UK AISI report: aisi.gov.uk/blog/how-fast-is…
Dave Guarino retweeted
Skepticism of corporate marketing and AI boosterism is always warranted, but I think the folks who accused Anthropic of overrating Mythos should check out this post by Mozilla developers indicating that the Firefox team fixed more security bugs in April using Mythos than in the past 15 months combined.
hacks.mozilla.org/2026/05/be…
I’ve worked at Anthropic for three weeks and I can say it is both wonderful and *quite* different from any other place I’ve ever worked. Feeling immense gratitude to get to work on the things I do (and concomitant obligation/responsibility.)
Dave Guarino retweeted
Over the past month, some of you reported Claude Code's quality had slipped. We investigated, and published a post-mortem on the three issues we found.
All are fixed in v2.1.116+ and we’ve reset usage limits for all subscribers.
Dave Guarino retweeted
Fast follow on my "What 81k people want from AI" work — this time, focused on the economic stuff: who's worried about their job, who's getting faster, and where the productivity gains are landing.
Findings include:
1. People are quite well-calibrated on personal job threat when we compare to observed job exposure
2. The biggest productivity gains go to the highest _and_ lowest-paid jobs
Last month, we published our look into what 81,000 people told us they want from AI.
In new research, we’ve investigated the economic hopes and worries referenced in their responses.
Read more: anthropic.com/research/81k-e…
Dave Guarino retweeted
Wow I can already say after just 5 hours using @AnthropicAI Opus 4.7 that this is the first model that "gets" what I'm doing when I'm working. It feels aligned with me in a way no previous model did.
(4.6 actively worked against me. I hated it. So this is *very* exciting!)
Some news! Last week I joined @AnthropicAI to help state and local governments safely and effectively deploy AI capabilities.
Personally I see profound opportunity to transform how public services are delivered & accessed—and I feel a deep responsibility to help that go well.





















