Prompt Engineering for Claude
How you phrase a request in the Claude Code chat panel determines the quality of what comes back. These principles work the same whether you are drafting copy, reviewing code, or planning a project.
Give Claude a Role
Start your message with who Claude should be: "Act as ThreadCo's brand copywriter — friendly, direct, never corporate." This calibrates tone, vocabulary, and depth without you having to specify every constraint.
Add Context with @files
Instead of pasting content into the chat, type @brandguide.md or @returns-policy.pdf. Claude reads the file directly. The more relevant context you attach, the more precise the output.
Specify the Output Format
Never leave format to chance. Say exactly what you want: "Respond with a bullet list of 5 items, each under 15 words" or "Write two sentences only. No headings. No bullet points."
Use Negative Constraints
"Do not use the words vibrant, perfect, or stylish. Do not use exclamation marks." Negative constraints are as powerful as positive ones — they cut exactly what you don't want.
Ask for Reasoning First
For complex tasks, add "Think through this step by step before answering." Claude reasons out loud, which surfaces assumptions you can correct before the final output is produced.
ThreadCo in the Claude Code Chat Panel
| Weak prompt | Strong prompt | Why it's better |
|---|---|---|
| Write a product description | You are a ThreadCo copywriter. Write a 2-sentence description for @sunset-tee.md. No exclamation marks. Mention the organic cotton. | Role + context file + format + constraint |
| Fix this bug | @orders.ts line 42 is throwing a null reference error. The stack trace is below. Fix the root cause — don't just add a null check. | Exact location + error + intent |
| Summarise the emails | @emails-this-week.txt — identify the top 3 customer complaints. For each: one sentence summary, suggested action, and who owns it. | Source file + structured output format |
| Make this better | @homepage-copy.md — rewrite for clarity. Target: someone who has never heard of ThreadCo. Keep it under 80 words. Do not change the tone. | Audience + word limit + preservation constraint |