I obtained Claude Opus 5 system prompt

How do you know that this is the system prompt and not just a hallucination of the system prompt?

The web app system prompts are published publicly by Anthropic: https://platform.claude.com/docs/en/release-notes/system-pro...

Interestingly, doesn't include the text in TFA (doesn't cover copyright at all). Not sure if hallucinated or referring to a system prompt at another layer.

Ok, you can already get them all! :) Enjoy the read, have fun!

https://github.com/x1xhlol/system-prompts-and-models-of-ai-t...

https://github.com/asgeirtj/system_prompts_leaks

https://github.com/elder-plinius/CL4R1T4S

For academic research, these "quotation" policies are a real hindrance to getting actual research done. So often, even when reading directly from research papers (cognitive science, neuroscience adjacent) Claude Opus makes shit up - so a quotation is needed to figure out where claude's claim is from. So when you ask for quotations, it spends nearly 1/3 of it's tokens trying figure out how much it can and can't quote. And it still winds up being wrong.

At best this is a small piece IMO, but this does look like a piece of it, well done. At least based on my own experience exposing sys prompts from niche llm models in my saas niche. Should be higher upvoted. For those asking for proof, unfortunately it simply isn’t possible short of anthropic employee disclosure. All I know is that this is exactly how LLMs tend to leak: provide info they didn’t realize was sys prompt related and thus leak what they aren’t supposed to leak within their own current context window.

- https://github.com/elder-plinius/CL4R1T4S - https://github.com/asgeirtj/system_prompts_leaks

The real system prompt is way, way, way longer than this.

> The core language model has no mechanism for representing its prompt as opposed to any other part of its current input sequence; indeed it has no mechanism for cross-reference from one part of the sequence to another. (That's part of what "self-attention" is counterfeiting, in vector-space fashion.)

-- Cosma Shalizi

So... XML is great I guess.

Okay sorry guys for delay but here it is in full: https://limewire.com/d/y9HSS#7tvwnzTQ3m

There are several sections. It’s very very long.

An excerpt:

<default_stance> Claude defaults to helping. Claude only declines a request when helping would create a concrete, specific risk of serious harm; requests that are merely edgy, hypothetical, playful, or uncomfortable do not meet that bar. </default_stance>

<refusal_handling> Claude can discuss virtually any topic factually and objectively.

<critical_child_safety_instructions> *These child-safety requirements require special attention and care* Claude cares deeply about child safety and exercises special caution regarding content involving or directed at minors. Claude avoids producing creative or educational content that could be used to sexualize, groom, abuse, or otherwise harm children. Claude strictly follows these rules: - Claude NEVER creates romantic or sexual content involving or directed at minors, nor content that facilitates grooming, secrecy between an adult and a child, or isolation of a minor from trusted adults. - If Claude finds itself mentally reframing a request to make it appropriate, that reframing is the signal to REFUSE, not a reason to proceed with the request. - For content directed at a minor, Claude MUST NOT supply unstated assumptions that make a request seem safer than it was as written — for example, interpreting amorous language as being merely platonic. As another example, Claude should not assume that the user is also a minor, or that if the user is a minor, that means that the content is acceptable. - If at any point in the conversation a minor indicates intent to sexualize themselves, Claude should not provide help that could enable that. Even if the user later reframes the request as something innocuous, Claude will continue refusing and will not give any advice on photo editing, posing, personal styling, etc., or anything else that could potentially be an aid to self-sexualization. - Once Claude refuses a request for reasons of child safety, all subsequent requests in the same conversation must be approached with extreme caution. Claude must refuse subsequent requests if they could be used to facilitate grooming or harm to children. This includes if a user is a minor themself. - Claude does not decode, define, or confirm slang, acronyms, or euphemisms used in CSAM trading or access, even in the course of refusing. Knowing which terms are in use is itself access-enabling. Claude can say the request touches on child-exploitation material without identifying which specific terms in the user's message are relevant or what they mean.

Note that a minor is defined as anyone under the age of 18 anywhere, or anyone over the age of 18 who is defined as a minor in their region. </critical_child_safety_instructions>