R0020/2026-03-25/Q003/SRC01/E02¶
Anthropic explicitly recommends reducing imperative enforcement language for newer models
URL: https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/claude-prompting-best-practices
Extract¶
Direct quote from Anthropic's documentation regarding Claude Opus 4.5 and Claude Opus 4.6:
"Claude Opus 4.5 and Claude Opus 4.6 are also more responsive to the system prompt than previous models. If your prompts were designed to reduce undertriggering on tools or skills, these models may now overtrigger. The fix is to dial back any aggressive language. Where you might have said 'CRITICAL: You MUST use this tool when...', you can use more normal prompting like 'Use this tool when...'"
Additional migration guidance: - "Tune anti-laziness prompting: If your prompts previously encouraged the model to be more thorough or use tools more aggressively, dial back that guidance." - "Replace blanket defaults with more targeted instructions. Instead of 'Default to using [tool],' add guidance like 'Use [tool] when it would enhance your understanding of the problem.'" - "Remove over-prompting. Tools that undertriggered in previous models are likely to trigger appropriately now."
Relevance to Hypotheses¶
| Hypothesis | Relationship | Strength |
|---|---|---|
| H1 | Contradicts | Vendor explicitly recommends reducing imperative language |
| H2 | Contradicts | The topic is discussed, even if the recommendation is to use less of it |
| H3 | Supports | Demonstrates the evolution from imperative to explanatory constraint style |
Context¶
This is the most diagnostic evidence for Q003. A major AI vendor is explicitly telling users to dial back enforcement language ("CRITICAL: You MUST") in favor of conversational constraints ("Use this tool when..."). This suggests that imperative constraints were a necessary workaround for less capable models, and that as models improve, the need for enforcement language decreases. The implication for structured research prompts is significant — prompts designed with RFC 2119-style MUST/MUST NOT language may need to evolve.
Notes¶
This guidance is specific to Claude 4.5/4.6 models (released 2025-2026). It may not apply to less capable models or other vendors' products. The trend is model-generation-dependent.