A lab deletes 80% of its agent's system prompt

Claim

Anthropic deleted 80% of Claude Code's system prompt, as the new models thrive on judgment over rules, while the system card rated Opus 5 the most aligned Claude yet — sharp at finding vulnerabilities, dull at weaponizing them.

Reported metric: -80% of prompt

Reporting date: 2026-07-26 (not necessarily the event date)

Sources

Attribution and reporting linked by this record; links do not imply independent verification.

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