Prompt-craft: context, role, format, iterate
Goal. Get sharper answers by giving Claude four things — context, a role, the output format you want, and structure — then iterating instead of restarting.
You are a careful biostatistics reviewer. <context> I ran a 3-arm dose-response experiment (control, low, high), n=6 per arm, and used a one-way ANOVA followed by Tukey's test. </context> <task> List, as a numbered checklist, the assumptions I should have checked before trusting this analysis, and for each one name the quick diagnostic I'd run. </task>
Anthropic's own guidance: wrap distinct parts of a prompt in simple tags like <context> and <task> so Claude can tell instructions from data. Setting a role ("You are a careful biostatistics reviewer") focuses its tone and rigor.
- 1Give context and a role. "You are a careful biostatistics reviewer" plus a sentence of background beats a bare question — Claude tailors depth and tone to the role you name.
- 2Ask for a specific format. "As a numbered checklist", "in three bullet points", "as a short paragraph I can paste into my methods" — saying the shape you want is the fastest way to get it.
- 3Structure with tags, then iterate. Anthropic recommends wrapping pieces in tags like
<context>,<task>,<data>so nothing gets confused. If the answer misses, don't start over — reply "tighten point 3" or "now do the same for a paired design".
You'll see. A focused, correctly-formatted answer the first time — and when you reply with a small correction, a revised version rather than a fresh start.
Cost. Free on every plan — prompt-craft costs nothing and is the single biggest lever on answer quality, on the free tier as much as on Pro.
Takeaway. Tell Claude who it is, give it context, name the output format, and wrap the parts in tags — then refine by replying, not by re-asking from scratch.