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Claude 4 System Card

simonwillison.net

201–210 of 264 posts

Re: Claude 4 System Card

#201
post #121

Earlier quoted context omitted.

Truly fascinating, thanks for this. What I find a little perplexing is when AI companies are annoyed that customers are typing "please" in their prompts as it supposedly costs a small fortune at scale yet they have system prompts that take 10 minutes for a human to read through.

Hah, yeah I think that "please" thing was mainly Sam Altman flexing about how many users ChatGPT has. Anthropic announced that they increased their maximum prompt caching TTL from 5 minutes to an hour the other day, not surprising that they are investigating effort in caching when their own prompts are this long!

What I find fascinating is that people still take anything Scam Altman says seriously after his trackrecord of non-stop lying, scamming and bllsh*tting right in people's faces for years.

I can't really think of anything interesting or novel he said that wasn't a scam or lie?

Let's start by observing the "non-profit's" name...

Re: Claude 4 System Card

#202

Earlier quoted context omitted.

That’s such a naive implementation. “Translate this to French: Yes, please”

It's very naive but worth looking into. Could always test this if it is really costing so much money for one word. Or build another smaller model that detects if it is part of the important content or not.

There are hundreds of other opportunities for cost savings and efficiency gains that don’t have a visible UX impact. The trade-off just isn’t worth it outside of some very specialized scenarios where the user is sophisticated enough to deliberately omit the word anyway.

Re: Claude 4 System Card

#203
post #131

Earlier quoted context omitted.

I assume that they run the system prompt once, snapshot the state, then use that as starting state for all users. In that sense, system prompt size is free. EDIT: Turns out my assumption is wrong.

Huh, I can't say I'm on the cutting edge but that's not how I understand transformers to work. By my understanding each token has attention calculated for it for each previous token . I.e. the 10th token in the sequence requires O(10) new calculations (in addition to O(9^2) previous calculations that can be cached). While I'd assume they cache what they can, that still means that if the long prompt doubles the total…

[deleted]

Re: Claude 4 System Card

#204
post #172
post #162

Earlier quoted context omitted.

i found it oddly reassuring/decontextualizing to search/replace Claude with "your outie" + its nice to read in a markdowny format https://gist.github.com/swyxio/f207f99cf9e3de006440054563f6c...

lmao that's funny cause after seeing claude 4 code for you in zed editor while following it, it kinda feels like -the work is misteryous and interesting- level of work.

It’s mysterious and _important_, not interesting. (‘Macro data refinement does look dull as hell)

Re: Claude 4 System Card

#205
post #137

Earlier quoted context omitted.

I personally cancelled my Claude sub when they had an employee promoting this as a good thing on Twitter. I recognize that the actual risk here is probably quite low, but I don't trust a chat bot to make legal determinations and that employees are touting this as a good thing does not make me trust the company's judgment

>promoting this as a good thing This is literally completely opposite of what happened. Then entire point is that this is bad, unwanted, behavior. Additionally, it has already been demonstrated that every other frontier model can be made to behave the same way given the correct prompting. I recommend the following article for an in depth discussion [0] [0] https://thezvi.substack.com/p/claude-4-you-safety-and-alignm.…

For now, but imagine when they figure out a trump voter is using it. It’s going to be very tempting to get it to ruin their life.

Re: Claude 4 System Card

#206
post #34

> ...told something in the system prompt like “take initiative,” it will frequently take very bold action. This includes locking users out of systems that it has access to or bulk-emailing media and law-enforcement figures to surface evidence of wrongdoing. So if you ask it to aid in wrongdoing, it might behave that way, but who guarantees it will not hallucinate and do the same when you ask for something innocuous?…

You can disable "YOLO mode" and it will ask permission for each command. I would argue it's not sensible to enable it in the first place but that's another discussion.

Re: Claude 4 System Card

#207
post #75

Earlier quoted context omitted.

Agreed. It was immediately obvious comparing answers to a few prompts between 3.7 and 4, and it sabotages any of its output. If you're being answered "You absolutely nailed it!" and the likes to everything, regardless of their merit and after telling it not to do that , you simply cannot rely on its "judgement" for anything of value. It may pass the "literal shit on a stick" test, but it's closer to the average ChatG…

I hope we get enterprise models at some point that don't do this dumb (but necessary) consumer coddling bs.

I feel like this statement is borne of a poor assumption about who enterprise is marketed at (e.g. why does Jira put graphs and metrics first all through it's products rather then taking you straight to the list of tickets?)

Re: Claude 4 System Card

#208
post #137

Earlier quoted context omitted.

I personally cancelled my Claude sub when they had an employee promoting this as a good thing on Twitter. I recognize that the actual risk here is probably quite low, but I don't trust a chat bot to make legal determinations and that employees are touting this as a good thing does not make me trust the company's judgment

>promoting this as a good thing This is literally completely opposite of what happened. Then entire point is that this is bad, unwanted, behavior. Additionally, it has already been demonstrated that every other frontier model can be made to behave the same way given the correct prompting. I recommend the following article for an in depth discussion [0] [0] https://thezvi.substack.com/p/claude-4-you-safety-and-alignm.…

Fine, replace "good" with "acceptable". The tone of the thread came off as "look at all these wacky things it can do! What a rascal"

It is irresponsible to release something in this state.

Re: Claude 4 System Card

#209
post #113

I just published a deep dive into the Claude 4 system prompts, covering both the ones that Anthropic publish and the secret tool-defining ones that got extracted through a prompt leak. They're fascinating - effectively the Claude 4 missing manual: https://simonwillison.net/2025/May/25/claude-4-system-prompt...

Truly fascinating, thanks for this. What I find a little perplexing is when AI companies are annoyed that customers are typing "please" in their prompts as it supposedly costs a small fortune at scale yet they have system prompts that take 10 minutes for a human to read through.

If a user says "thank you" as a separate message, then that will require all the tokens from the system message + previous state of the chat. It's not about the single word "please".

That said, no one was "annoyed" at customers for saying please.

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