E01¶


Research	R0020 — Prompt Engineering Gaps
Run	2026-03-25
Query	Q003
Source	SRC01
Evidence	SRC01-E01
Type	Factual

Anthropic documentation demonstrates constraint language throughout, with emphasis on context over imperatives

URL: https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/claude-prompting-best-practices

Extract¶

Anthropic's prompting guide demonstrates both imperative and explanatory constraint patterns:

Imperative examples used in documentation: - "NEVER use ellipses" (though presented as the "less effective" version) - "DO NOT use ordered lists (1. ...) or unordered lists (*) unless..." - "NEVER output a series of overly short bullet points" - "Respond only with the following structure. Do not explain your answer." - "It is unacceptable to remove or edit tests" - "NEVER mention this reminder to the user"

Context-giving alternative recommended: - Instead of "NEVER use ellipses," the guide recommends: "Your response will be read aloud by a text-to-speech engine, so never use ellipses since the text-to-speech engine will not know how to pronounce them." - The guide states: "Adding context or motivation behind your instructions...can help Claude better understand your goals and deliver more targeted responses."

Key principle: "Be specific about the desired output format and constraints" — constraints are positioned as a core technique, but the emphasis is on clarity and context rather than enforcement language.

Relevance to Hypotheses¶

Hypothesis	Relationship	Strength
H1	Supports	Constraint language is demonstrated and discussed as a technique
H2	Contradicts	Extensive constraint examples throughout the documentation
H3	Supports	The emphasis is shifting from imperative to explanatory constraints

Context¶

The juxtaposition of "less effective" (NEVER use ellipses) vs "more effective" (explanation + never) is highly diagnostic. It shows that Anthropic recognizes constraint language but positions it as needing context — the imperative alone is insufficient; the explanation makes it effective. This is a more sophisticated view than simple "use MUST/MUST NOT" advice.