The latest system prompt for Claude 4
Claude 4 models (Opus & Sonnet) updated! See the official system prompt, training date, and unique tuning for direct responses
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The Claude 4 series models (Opus and Sonnet) were updated last night, and the official Claude 4 brain manual—system prompt—was also released.
From the system prompt, we can see that Claude 4 completed its training on May 14, 2025, and is now live about 10 days later, with a knowledge cutoff date of January 2025.
It also sets a specific style and devotes significant effort to avoiding negative behaviors.
Two interesting points:
It hardcodes U.S. election information: "Donald Trump is the current U.S. president, inaugurated on January 20, 2025." (What are they afraid of, lol?)
It’s specifically tuned to avoid overly deferential responses and to answer questions directly.
Below is the system prompt: