Plinius leaks full Claude Opus-5.5 system prompt, over 1.9M characters with tools
ivan_bezdomny · x · 2026-09-23
Security researcher elderplinius published what he claims is the complete system prompt of Claude Opus-5.5 in his GitHub repo CL4R1T4S. Including all tool definitions, the extraction totals over 1.9M characters (21.5K lines, 1.86 MB). The repo, which aggregates leaked system prompts across vendors, has 50K+ stars, and the sheer size of this prompt is fueling discussion about how complex frontier-model system instructions have become.
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