Sometimes Claude''s answer is so long it buries the point, and other times it is too short to be useful. Stating the length and level of detail you want up front gets you just the right amount.
Words that control length
The easiest approach is to state the amount you want. To go shorter: "in one sentence", "just the top three", "summarize in one paragraph". To go longer: "explain in detail with examples", "start from the background" — naming the depth along with the length.
Detail and depth
You can adjust depth as well as length. "Explain simply for a beginner" adds background; "for an expert, key points only" trims the filler. Telling Claude who the reader is helps it match the depth.
Specify tone too
The same content varies in length by tone. Adding "keep it formal" or "conversational" sets the length and the feel at once.
Limits to keep in mind
A request like "exactly 100 characters" may not be met precisely, because Claude generates by meaning units rather than counting characters. Relative cues — "shorter / longer / three points / one paragraph" — work better than exact counts. If the length is off, just follow up: "shorter" or "a bit more detail".
Reference: general prompting principles are documented in Anthropic''s official docs (docs.claude.com).