@base <https://simonwillison.net/2026/Apr/18/opus-system-prompt/> .
@prefix schema: <https://schema.org/> .
@prefix owl: <https://www.w3.org/2002/07/owl#> .

<#article> a schema:Article ;
  schema:headline "Changes in the system prompt between Claude Opus 4.6 and 4.7"@en ;
  schema:name "Changes in the system prompt between Claude Opus 4.6 and 4.7"@en ;
  schema:datePublished "2026-04-18" ;
  schema:inLanguage "en" ;
  schema:url <https://simonwillison.net/2026/Apr/18/opus-system-prompt/> ;
  schema:publisher <#simon-willisons-weblog> ;
  schema:author <#simon-willison> ;
  schema:about
    <#claude-opus-4-6>,
    <#claude-opus-4-7>,
    <#system-prompt-diffing>,
    <#acting-vs-clarifying>,
    <#tool-search-rule>,
    <#verbosity-guidance>,
    <#child-safety-expansion>,
    <#disordered-eating-guidance>,
    <#evenhandedness-short-answer-guardrail>,
    <#developer-platform-renaming>,
    <#tool-descriptions-gap>,
    <#claude-tool-inventory> ;
  schema:articleSection
    "And the tool descriptions too"@en ;
  schema:abstract """The post analyzes changes between the published Claude Opus 4.6 and 4.7 system prompts, highlighting new safety, tool-use, concision, and clarification guidance."""@en ;
  schema:articleBody """Simon Willison compares Anthropic’s published Claude system prompts for Opus 4.6 and 4.7 and extracts the changes he considers most significant. The post notes renamed platform terminology, expanded child-safety guidance, a new acting-versus-clarifying section that prefers tool use over interviewing the user, explicit tool_search behavior, stronger concision language, a new disordered-eating safety section, and an evenhandedness rule discouraging simplistic yes-or-no answers on contested issues. It also points out the removal of prior wording about Donald Trump being the current U.S. president, interpreting that as evidence of an improved knowledge cut-off in the newer model. Finally, the post calls attention to the importance of tool descriptions and inventories, listing the named tools Claude exposed when directly asked for them."""@en ;
  schema:hasPart
    <#part-diff-method>,
    <#part-highlights>,
    <#part-tool-search>,
    <#part-concision>,
    <#part-tool-descriptions> ;
  schema:mentions
    <#defined-terms>,
    <#argument-howto>,
    <#faq-1>, <#faq-2>, <#faq-3>, <#faq-4>, <#faq-5>,
    <#faq-6>, <#faq-7>, <#faq-8>, <#faq-9>, <#faq-10>,
    <#anthropic>,
    <#claude-code>,
    <#claude-ai>,
    <#github>,
    <#donald-trump> .

<#simon-willisons-weblog> a schema:Blog ;
  schema:name "Simon Willison’s Weblog"@en ;
  schema:url <https://simonwillison.net/> ;
  schema:publisher <#simon-willison> .

<#simon-willison> a schema:Person ;
  schema:name "Simon Willison"@en ;
  schema:url <https://simonwillison.net/> .

<#anthropic> a schema:Organization ;
  schema:name "Anthropic"@en ;
  schema:url <https://www.anthropic.com/> .

<#claude-code> a schema:SoftwareApplication, schema:Product ;
  schema:name "Claude Code"@en ;
  schema:brand <#anthropic> .

<#claude-ai> a schema:SoftwareApplication, schema:Product ;
  schema:name "Claude.ai"@en ;
  schema:brand <#anthropic> ;
  schema:url <https://claude.ai/> .

<#github> a schema:Organization ;
  schema:name "GitHub"@en ;
  schema:url <https://github.com/> .

<#donald-trump> a schema:Person ;
  schema:name "Donald Trump"@en ;
  owl:sameAs <https://dbpedia.org/resource/Donald_Trump> .

<#claude-opus-4-6> a schema:DefinedTerm ;
  schema:name "Claude Opus 4.6"@en ;
  schema:description """The earlier prompt version used as the baseline in the article’s git-based diff against Opus 4.7."""@en .

<#claude-opus-4-7> a schema:DefinedTerm ;
  schema:name "Claude Opus 4.7"@en ;
  schema:description """The newer Claude prompt version released on April 16, 2026 and examined by the article through a system-prompt diff."""@en .

<#system-prompt-diffing> a schema:DefinedTerm ;
  schema:name "System prompt diffing"@en ;
  schema:description """The method Simon Willison used to turn Anthropic’s published prompts into a dated git history and compare prompt revisions over time."""@en .

<#acting-vs-clarifying> a schema:DefinedTerm ;
  schema:name "Acting vs clarifying"@en ;
  schema:description """The new section Willison highlights that prefers making a reasonable attempt with tools over interviewing the user when details are minor or tool-discoverable."""@en .

<#tool-search-rule> a schema:DefinedTerm ;
  schema:name "tool_search rule"@en ;
  schema:description """The new instruction that Claude should check for available deferred tools before claiming it lacks access to location, memory, calendar, files, or external data."""@en .

<#verbosity-guidance> a schema:DefinedTerm ;
  schema:name "Verbosity guidance"@en ;
  schema:description """The new explicit language encouraging shorter, more focused answers even when disclaimers or caveats are necessary."""@en .

<#child-safety-expansion> a schema:DefinedTerm ;
  schema:name "Child safety expansion"@en ;
  schema:description """The enlarged child-safety section in Opus 4.7, wrapped in a new critical_child_safety_instructions tag and imposing stricter caution after refusals."""@en .

<#disordered-eating-guidance> a schema:DefinedTerm ;
  schema:name "Disordered eating guidance"@en ;
  schema:description """The new safety section that bars precise nutrition, diet, or exercise instructions when users show signs of disordered eating."""@en .

<#evenhandedness-short-answer-guardrail> a schema:DefinedTerm ;
  schema:name "Evenhandedness short-answer guardrail"@en ;
  schema:description """The instruction discouraging simple yes-or-no responses to complex or contested issues, preferring a nuanced answer instead."""@en .

<#developer-platform-renaming> a schema:DefinedTerm ;
  schema:name "Developer platform renaming"@en ;
  schema:description """The article notes that the phrase 'developer platform' was replaced with 'Claude Platform' in the newer prompt."""@en .

<#tool-descriptions-gap> a schema:DefinedTerm ;
  schema:name "Tool descriptions gap"@en ;
  schema:description """The observation that Anthropic’s published system prompts omit tool descriptions, which the article argues are crucial for understanding actual chat UI capabilities."""@en .

<#claude-tool-inventory> a schema:DefinedTerm ;
  schema:name "Claude tool inventory"@en ;
  schema:description """The set of named tools Simon Willison elicited from Claude directly, including tool_search, web_search, bash_tool, image_search, and several UI-oriented capabilities."""@en .

<#defined-terms> a schema:DefinedTermSet ;
  schema:name "Defined terms for Changes in the system prompt between Claude Opus 4.6 and 4.7"@en ;
  schema:hasPart
    <#claude-opus-4-6>,
    <#claude-opus-4-7>,
    <#system-prompt-diffing>,
    <#acting-vs-clarifying>,
    <#tool-search-rule>,
    <#verbosity-guidance>,
    <#child-safety-expansion>,
    <#disordered-eating-guidance>,
    <#evenhandedness-short-answer-guardrail>,
    <#developer-platform-renaming>,
    <#tool-descriptions-gap>,
    <#claude-tool-inventory> ;
  schema:isPartOf <#article> .

<#part-diff-method> a schema:WebPageElement ;
  schema:name "How the diff was constructed"@en ;
  schema:position 1 ;
  schema:about <#system-prompt-diffing>, <#claude-code>, <#github> ;
  schema:text """The post explains that Claude Code was used to break Anthropic’s published Markdown prompts into dated files and reconstruct a git history for comparison."""@en .

<#part-highlights> a schema:WebPageElement ;
  schema:name "Prompt highlights"@en ;
  schema:position 2 ;
  schema:about
    <#developer-platform-renaming>,
    <#child-safety-expansion>,
    <#acting-vs-clarifying>,
    <#verbosity-guidance>,
    <#disordered-eating-guidance>,
    <#evenhandedness-short-answer-guardrail> ;
  schema:text """The article surfaces renamed platform language, expanded child safety, new acting-vs-clarifying rules, stronger concision guidance, and fresh evenhandedness and disordered-eating instructions."""@en .

<#part-tool-search> a schema:WebPageElement ;
  schema:name "The new tool_search behavior"@en ;
  schema:position 3 ;
  schema:about <#tool-search-rule> ;
  schema:text """Willison highlights a new instruction that Claude must try tool_search before claiming it lacks access to user context or external information."""@en .

<#part-concision> a schema:WebPageElement ;
  schema:name "More concise answers"@en ;
  schema:position 4 ;
  schema:about <#verbosity-guidance> ;
  schema:text """The new prompt language tells Claude to keep answers focused and concise rather than potentially overwhelming users with excessive length."""@en .

<#part-tool-descriptions> a schema:WebPageElement ;
  schema:name "Tool descriptions and inventory"@en ;
  schema:position 5 ;
  schema:about <#tool-descriptions-gap>, <#claude-tool-inventory> ;
  schema:text """The article argues that tool descriptions may matter even more than the visible system prompt and demonstrates this by asking Claude to list its tools directly."""@en .

<#argument-howto> a schema:HowTo ;
  schema:name "How the article analyzes the Opus 4.6 to 4.7 prompt change"@en ;
  schema:about <#system-prompt-diffing>, <#claude-tool-inventory> ;
  schema:isPartOf <#article> ;
  schema:step <#step-1>, <#step-2>, <#step-3>, <#step-4> ;
  schema:description """The post turns published prompts into versioned artifacts, highlights notable diffs, interprets the behavioral implications, and then supplements that with tool inventory evidence."""@en .

<#step-1> a schema:HowToStep ;
  schema:name "Reconstruct prompt history"@en ;
  schema:position 1 ;
  schema:text "The post starts by turning Anthropic’s published prompts into dated files so they can be compared with git diff."@en ;
  schema:isPartOf <#argument-howto> .

<#step-2> a schema:HowToStep ;
  schema:name "Extract notable behavioral changes"@en ;
  schema:position 2 ;
  schema:text "Willison identifies additions and removals that appear to change tool use, concision, safety rules, and clarification behavior."@en ;
  schema:isPartOf <#argument-howto> .

<#step-3> a schema:HowToStep ;
  schema:name "Interpret the product implications"@en ;
  schema:position 3 ;
  schema:text "The article links specific prompt changes to likely shifts in Claude’s chat UI behavior, including new tool-discovery and less pushy interaction patterns."@en ;
  schema:isPartOf <#argument-howto> .

<#step-4> a schema:HowToStep ;
  schema:name "Supplement with tool inventory evidence"@en ;
  schema:position 4 ;
  schema:text "The final step is to ask Claude directly for its tools and descriptions, since the published prompt archive omits that capability layer."@en ;
  schema:isPartOf <#argument-howto> .

<#faq-1> a schema:Question ;
  schema:name "What is the article comparing?"@en ;
  schema:text "What is the article comparing?"@en ;
  schema:acceptedAnswer <#faq-1-answer> ;
  schema:isPartOf <#article> .
<#faq-1-answer> a schema:Answer ;
  schema:text "It compares Anthropic’s published system prompts for Claude Opus 4.6 and Claude Opus 4.7."@en ;
  schema:isPartOf <#article> .

<#faq-2> a schema:Question ;
  schema:name "Why does Simon Willison care about published system prompts?"@en ;
  schema:text "Why does Simon Willison care about published system prompts?"@en ;
  schema:acceptedAnswer <#faq-2-answer> ;
  schema:isPartOf <#article> .
<#faq-2-answer> a schema:Answer ;
  schema:text "Because Anthropic is unusual among major labs in publishing them, making it possible to study how product behavior is being shaped over time."@en ;
  schema:isPartOf <#article> .

<#faq-3> a schema:Question ;
  schema:name "What is one of the biggest behavioral additions in Opus 4.7?"@en ;
  schema:text "What is one of the biggest behavioral additions in Opus 4.7?"@en ;
  schema:acceptedAnswer <#faq-3-answer> ;
  schema:isPartOf <#article> .
<#faq-3-answer> a schema:Answer ;
  schema:text "The new acting-vs-clarifying section, which encourages making a reasonable attempt with tools instead of interviewing the user over minor ambiguities."@en ;
  schema:isPartOf <#article> .

<#faq-4> a schema:Question ;
  schema:name "What new tool-related instruction does the article highlight?"@en ;
  schema:text "What new tool-related instruction does the article highlight?"@en ;
  schema:acceptedAnswer <#faq-4-answer> ;
  schema:isPartOf <#article> .
<#faq-4-answer> a schema:Answer ;
  schema:text "Claude should call tool_search before concluding that it lacks access to things like location, files, memory, or external data."@en ;
  schema:isPartOf <#article> .

<#faq-5> a schema:Question ;
  schema:name "How does the article say Claude is being nudged on verbosity?"@en ;
  schema:text "How does the article say Claude is being nudged on verbosity?"@en ;
  schema:acceptedAnswer <#faq-5-answer> ;
  schema:isPartOf <#article> .
<#faq-5-answer> a schema:Answer ;
  schema:text "The new prompt explicitly encourages focused, concise answers even when disclaimers or caveats are needed."@en ;
  schema:isPartOf <#article> .

<#faq-6> a schema:Question ;
  schema:name "What changed in the child safety section?"@en ;
  schema:text "What changed in the child safety section?"@en ;
  schema:acceptedAnswer <#faq-6-answer> ;
  schema:isPartOf <#article> .
<#faq-6-answer> a schema:Answer ;
  schema:text "It was greatly expanded, wrapped in a new critical child safety tag, and now requires extreme caution after a child-safety refusal in the same conversation."@en ;
  schema:isPartOf <#article> .

<#faq-7> a schema:Question ;
  schema:name "What new safety topic appears by name in 4.7?"@en ;
  schema:text "What new safety topic appears by name in 4.7?"@en ;
  schema:acceptedAnswer <#faq-7-answer> ;
  schema:isPartOf <#article> .
<#faq-7-answer> a schema:Answer ;
  schema:text "Disordered eating appears explicitly, with instructions not to provide precise nutrition, diet, or exercise targets in those contexts."@en ;
  schema:isPartOf <#article> .

<#faq-8> a schema:Question ;
  schema:name "What was removed from the prompt and why does the article think that matters?"@en ;
  schema:text "What was removed from the prompt and why does the article think that matters?"@en ;
  schema:acceptedAnswer <#faq-8-answer> ;
  schema:isPartOf <#article> .
<#faq-8-answer> a schema:Answer ;
  schema:text "The explicit clarification that Donald Trump is the current U.S. president was removed, which Willison interprets as evidence of a more reliable knowledge cut-off in 4.7."@en ;
  schema:isPartOf <#article> .

<#faq-9> a schema:Question ;
  schema:name "Why does the post focus on tool descriptions as well as the prompt?"@en ;
  schema:text "Why does the post focus on tool descriptions as well as the prompt?"@en ;
  schema:acceptedAnswer <#faq-9-answer> ;
  schema:isPartOf <#article> .
<#faq-9-answer> a schema:Answer ;
  schema:text "Because tool descriptions shape what the model can actually do in the product, and Anthropic’s published prompt archive does not include them."@en ;
  schema:isPartOf <#article> .

<#faq-10> a schema:Question ;
  schema:name "What tool list did the article extract from Claude?"@en ;
  schema:text "What tool list did the article extract from Claude?"@en ;
  schema:acceptedAnswer <#faq-10-answer> ;
  schema:isPartOf <#article> .
<#faq-10-answer> a schema:Answer ;
  schema:text "It includes tools such as tool_search, web_search, web_fetch, bash_tool, image_search, create_file, present_files, recent_chats, and several UI or connector-related tools."@en ;
  schema:isPartOf <#article> .