AI Guides › Prompting
Why Longer Prompts Aren't More Precise Prompts
By Nigel Guy · 2 min read
When an answer comes back wrong, the instinct is to add — another sentence
of context, another caveat, another clarifying clause tacked on to the end.
It feels like progress, because the prompt now visibly contains more
information. But length and precision are different things, and a prompt can
grow for a while in exactly the direction that makes it harder to act on: more
context, more hedges, more half-relevant detail, and no clearer statement of
what's actually being asked.
The rule: length adds words; precision removes ambiguity — a prompt can
gain the first while losing the second, and past a point, more words actively
bury the request.
Why longer can get worse, not better
- Every added sentence is something else to weigh. A ten-constraint
prompt forces a judgement call about which constraints matter most, and
that call gets made silently, without you.
- Context isn't the same as instruction. Background on why you need
something is useful once; restated three ways, it just crowds out the one
sentence that actually says what to produce.
- Hedges compound instead of cancelling out. "Roughly, but also try to
be precise, though it doesn't need to be exact" isn't a nuanced
instruction — it's three instructions in tension, and something has to
give.
- The core ask gets harder to find, not easier, the longer the prompt
runs — for a reader working through it top to bottom, the actual request
is often buried past the point where attention to any single sentence
starts to fade.
The mechanism
- Write the prompt, then find the single sentence that states the actual
request. If you can't point to it, the prompt hasn't got shorter or
longer — it's just missing that sentence.
- Cut anything that repeats a point already made, even in different
words. Restating "please make sure it's accurate" three ways adds length
without adding a new constraint.
- Move the essential constraints to the front, and let context follow
after — position does real work; the same sentence buried in paragraph
three is worth less than it is stated first.
- Check against the one-sentence test — if you can't summarise your own
request in one plain sentence once you're done, the added length didn't
help (see the guide on that test directly, for the full mechanism).
What to skip
Skip padding a prompt "to be safe" — extra caveats you don't actually need
usually just dilute the ones you do. And skip assuming a short prompt is
automatically clearer; brevity isn't the goal either. The target is the
fewest words that state the real constraints, not the fewest words full stop.
Guardrails
- A precise, well-ordered prompt still needs its output checked — precision
in the ask raises the odds of a good answer, it doesn't guarantee one.
- Some tasks genuinely need more words — a complex multi-part request isn't
wrong to be long, as long as every added sentence is doing distinct work.
- If you're unsure whether a prompt has drifted into padding, read it aloud;
redundant hedging is usually more obvious heard than skimmed.
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