{"slug": "we-removed-over-80-of-claude-code-s-system-prompt-for-opus-5-and-fable-5", "title": "\"We removed over 80% of Claude Code's system prompt for Opus 5 and Fable 5\"", "summary": "Anthropic removed over 80% of the Claude Code system prompt for its newest models Opus 5 and Fable 5, sharing lessons learned about writing system prompts, skills, and Claude.MDs for them. A user reported that Opus 5 is performing significantly better, particularly for biology tasks, after previously relying on Claude 4.6 and other models.", "body_md": "We removed ~80% of the Claude Code system prompt for our newest models, this is what we've learned about writing system prompts, skills and Claude.MDs for them.\n\n- Appreciate it! Opus 5 is performing a lot better Was stuck relying on 4.6 + other models for biology stuff until now\n# Join the conversation", "url": "https://wpnews.pro/news/we-removed-over-80-of-claude-code-s-system-prompt-for-opus-5-and-fable-5", "canonical_source": "https://twitter.com/trq212/status/2080710971228918066", "published_at": "2026-07-25 02:18:09+00:00", "updated_at": "2026-07-25 02:52:21.260874+00:00", "lang": "en", "topics": ["artificial-intelligence", "large-language-models", "ai-products", "ai-tools", "developer-tools"], "entities": ["Anthropic", "Claude Code", "Opus 5", "Fable 5", "Claude 4.6"], "alternates": {"html": "https://wpnews.pro/news/we-removed-over-80-of-claude-code-s-system-prompt-for-opus-5-and-fable-5", "markdown": "https://wpnews.pro/news/we-removed-over-80-of-claude-code-s-system-prompt-for-opus-5-and-fable-5.md", "text": "https://wpnews.pro/news/we-removed-over-80-of-claude-code-s-system-prompt-for-opus-5-and-fable-5.txt", "jsonld": "https://wpnews.pro/news/we-removed-over-80-of-claude-code-s-system-prompt-for-opus-5-and-fable-5.jsonld"}}