# "We removed over 80% of Claude Code's system prompt for Opus 5 and Fable 5" > Source: > Published: 2026-07-25 02:18:09+00:00 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. - Appreciate it! Opus 5 is performing a lot better Was stuck relying on 4.6 + other models for biology stuff until now # Join the conversation