Lean Prompting — Frequently Asked Questions
Common questions about prompt efficiency — how short is too short, when long prompts help, and how to measure prompt quality.
Your Questions Answered ❓
How short is too short?
A prompt is too short when it is ambiguous — when the AI has to guess what you mean rather than knowing. "Write about dogs" is too short. "Write a 200-word breed comparison of Labradors vs Golden Retrievers for first-time dog owners" is lean but complete. The goal is not minimum word count — it is maximum signal-to-noise ratio.
Do AI models actually perform better with shorter prompts?
Generally yes, up to a point. Research shows that removing irrelevant context improves output relevance by 15-25%. But this applies to removing noise, not information. A 200-word prompt full of useful context will outperform a 30-word prompt missing key details. The target is not "short" — it is "efficient."
Does being polite to AI waste tokens?
Saying "please" adds one token and has no measurable effect on output quality. Do not stress about politeness — stress about redundancy, hedging, and preambles. "Please write a summary of X" is fine. "I would really appreciate it if you could kindly help me out by writing a summary of X, if that is not too much trouble" is bloated.
How do I know if my prompt is efficient enough?
Apply the removal test: take out one sentence. Does the output change meaningfully? If no, that sentence was fat. Repeat until every removal changes the output. That is your lean prompt. Alternatively, use PromptPerfect to get an automated efficiency analysis.
Is there a difference between prompt efficiency for chat vs API?
Yes. In chat interfaces, slightly verbose prompts are fine — the cost is just time. In API calls at scale, every unnecessary token multiplies across thousands of requests. API users should aggressively optimise prompt length. Chat users should focus on clarity over brevity.
Can AI help me write leaner prompts?
Absolutely. One of the most useful meta-prompts: "Rewrite this prompt to be as concise as possible while preserving all essential requirements: [paste your prompt]." The AI will typically cut 30-50% of the words and preserve the meaning. Then use the lean version going forward.
What about system prompts — should those be lean too?
System prompts deserve more length because they set context for every subsequent interaction. A well-crafted system prompt with clear persona, constraints, and examples can make every user prompt shorter because the context is already established. Think of system prompts as infrastructure — invest more upfront, save on every subsequent call.