Prompt anatomy
Roles, instructions, context, and constraints — the four building blocks
Why most prompts underperform
Most people write prompts the way they would send a text message: brief, casual, context-free. That works for humans who share your world — it works poorly for Claude, which only knows what you tell it. A well-structured prompt is the difference between a generic response and one that actually fits your situation.
The four components
1. Role (who Claude should be)
Telling Claude to adopt a role activates patterns from that domain. “You are a senior copywriter specializing in B2B SaaS” pulls Claude toward a very different vocabulary and set of concerns than “you are a helpful assistant.”
You are an experienced operations consultant helping a bilingual digital agency owner improve client workflows.2. Instructions (what to do)
The actual task. Be specific about the action. “Write” vs “Analyze” vs “Compare” give Claude fundamentally different directives.
Audit the following client onboarding email sequence and identify the three biggest friction points a new client would encounter.3. Context (what Claude needs to know)
Background information that shapes the output: who the audience is, what constraints exist, relevant history, tone, format preferences. This is the most commonly underprovided component.
Context: The client is a mid-size Houston HVAC company, owner-operated, not very technical. They are onboarding for a new website project. The sequence currently has 4 emails over 2 weeks.4. Constraints (what NOT to do)
Negative instructions are often more powerful than positive ones. Telling Claude what to avoid, what format to skip, what length to stay under — these sharpen the output dramatically.
Do not use marketing jargon. Keep each recommendation under 2 sentences. Do not suggest rewriting the emails — focus only on structural issues.Tip: You don’t always need all four. A simple creative task might just need role + instructions. A complex analytical task needs all four. Start with what you have and add components when the output isn’t specific enough.
The anatomy in practice
| Weak prompt | What’s missing | Fix |
|---|---|---|
| “Write me an email” | Role, context, constraints | Add who’s writing, to whom, for what purpose, in what tone |
| “Analyze my data” | Instructions, context | Specify what analysis, what the data represents, what decision it’s for |
| “Make this better” | Everything except subject | Define better: shorter? more formal? more persuasive? |
Exercise: Take a prompt you use regularly. Label each sentence: Role / Instruction / Context / Constraint. Which component is missing? Add it and compare the output.