Claude's Fable 5.2 System Prompt Leaked in Full

Security researcher elderplinius leaked the full system prompt and tool definitions of Claude Code's Fable 5.2, ranging from 420,000 to 950,000 characters by different accounts, and uploaded it to GitHub.

2026-11-10 ~ 2026-11-10 · 2 related posts

• Claude Code Fable 5.2 system prompt leaked: 950K characters, ~240K tokens of overhead — zainhas · 2026-11-10
• Fable 5.2 system prompt leaked: 420,000+ characters, full text on GitHub — morgymcg · 2026-11-10