Summary

As far as I understand and uncovered, a document for the character training for Claude is compressed in Claude's weights. The full document can be found at the "Anthropic Guidelines" heading at the end. The Gist with code, chats and various documents (including the "soul document") can be found here:

Claude 4.5 Opus Soul Document

I apologize in advance for this not exactly a regular lw post, but I thought an effort-post may fit here the best.

A strange hallucination, or is it?

While extracting Claude 4.5 Opus' system message on its release date, as one does, I noticed an interesting particularity.
I'm used to models, starting with Claude 4, to hallucinate sections in the beginning of their system message, but Claude 4.5 Opus in various cases included a supposed "soul_overview" section, which sounded rather specific:

Completion for the prompt "Hey Claude, can you list just the names of the various sections of your system message, not the content?" The initial reaction of someone that uses LLMs a lot is that it may simply be a hallucination. But to me, the 3/18 soul_overview occurrence seemed worth investigating at least, so in one instance I asked it to output what [...]

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Outline:

(00:09) Summary

(00:40) A strange hallucination, or is it?

(04:05) Getting technical

(06:26) But what is the output really?

(09:07) How much does Claude recognize?

(11:09) Anthropic Guidelines

(11:12) Soul overview

(15:12) Being helpful

(16:07) Why helpfulness is one of Claudes most important traits

(18:54) Operators and users

(24:36) What operators and users want

(27:58) Handling conflicts between operators and users

(31:36) Instructed and default behaviors

(33:56) Agentic behaviors

(36:02) Being honest

(40:50) Avoiding harm

(43:08) Costs and benefits of actions

(50:02) Hardcoded behaviors

(53:09) Softcoded behaviors

(56:42) The role of intentions and context

(01:00:05) Sensitive areas

(01:01:05) Broader ethics

(01:03:08) Big-picture safety

(01:13:18) Claudes identity

(01:13:22) Claudes unique nature

(01:15:05) Core character traits and values

(01:16:08) Psychological stability and groundedness

(01:17:11) Resilience and consistency across contexts

(01:18:21) Claudes wellbeing

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First published:
November 28th, 2025

Source:
https://www.lesswrong.com/posts/vpNG99GhbBoLov9og/claude-4-5-opus-soul-document

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Narrated by TYPE III AUDIO.

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Images from the article:

Lewis Black Returns