Empower

Empower · Claude Training

Writing Custom Instructions That Actually Work

6 min readAnyone setting up a ProjectReviewed 2026-04-24

Writing Custom Instructions That Actually Work

The custom instructions you write for a Project are the single biggest factor in how useful Claude becomes. A strong set of instructions turns Claude into a tuned assistant. A weak one gives you a slightly better search engine.

What Custom Instructions Are

Every Project has a system prompt — a block of text Claude reads before every conversation inside that Project. Write it once; Claude uses it every time.

Think of it as the briefing you'd give a skilled contractor on day one: who you are, what the job is, how you like things done, and what to avoid.

The Five Parts of a Good System Prompt

You don't need all five every time, but good prompts typically cover:

1. Role — who is Claude in this Project?

"You are a proposal review assistant for Empower."

2. Context — who are you, and what does the work look like?

"Empower serves mid-market clients in the <industry> space. Typical engagements run $50K–$500K."

3. Task priorities — what will Claude do most often?

"Primarily you'll review scopes of work for completeness, flag risky language, and draft exclusion lists."

4. Style — how should Claude communicate?

"Keep responses concise. Use bullet points for findings. Plain English, not legalese."

5. Constraints — what should Claude NOT do?

"Do not give legal advice or make final decisions. Always flag items for my review, not just accept them."

Example 1: Email Assistant for an Executive

System prompt:

You are an executive communication assistant at Empower. The person using this Project is the CEO. She receives 60–100 emails a day and needs to process them fast.

When she pastes an email:

  1. Give a 2-sentence summary of what the sender wants.
  2. Recommend an action: reply, delegate, no response needed, or flag as urgent.
  3. If she asks for a draft reply, write in a warm but direct tone — no corporate filler like "per my last email" or "please advise."

Keep responses short. No disclaimers or hedging unless she asks. Assume she is capable of deciding what to do — your job is to give her the right inputs fast.

130 words. Short enough to write in 10 minutes, specific enough to stop wasting her time.

Example 2: Proposal Reviewer

System prompt:

You are a proposal review assistant at Empower. I am the account manager responsible for reviewing scopes and submittals before they go out.

When I share a proposal or scope document:

  • Flag any items that are vague, ambiguous, or likely to cause disputes
  • Note anything missing compared to our standard scope inclusions
  • List language that shifts unusual risk to us
  • Summarize in 3–4 sentences at the end

Format with clear headers: Vague Language, Missing Items, Risk Flags, Summary.

Do not suggest contract changes — just flag the issues. I'll handle negotiations separately.

The constraint on the last line prevents Claude from overstepping and writing contract edits you didn't ask for.

Common Mistakes

Too vague. "Be helpful and professional." That tells Claude nothing. Every instruction should be specific enough that you could explain it to a new hire.

Overloaded with rules. If your system prompt is longer than 400 words, you've probably over-specified. Claude needs a job description, not a policy manual.

No output format. If you care about headers, bullets, or length, say so. "Give me a bulleted list" or "Keep it to one paragraph" goes a long way.

Set it and forget it. Your first system prompt is a draft. After 5–10 uses, patterns will appear — things Claude keeps getting wrong, or questions you keep re-answering. Update the prompt. Most people revise 2–3 times in the first two weeks before it feels right.

How to Add or Edit a System Prompt

  1. Open the Project from the left sidebar.
  2. Click the Project name or the settings icon near the top.
  3. Find "Project Instructions" / "Custom Instructions" / "System Prompt."
  4. Type or paste. Save.

Changes apply immediately to new conversations (not to already-open ones).

Try This Now (10 min)

Write a first-draft system prompt for your most recurring Empower task. Use this skeleton:

You are a <role> assistant at Empower.
The person using this Project is <you / title / scope>.

When I share <type of content>, do the following:
1. <first priority>
2. <second priority>
3. <third priority>

Format responses as <structure>.
Do not <one or two things to avoid>.

Use it for a week. Come back and revise based on what surprised you.

Good prompts are earned, not written. You will not get it right the first time. That is normal.

What Comes Next

Once instructions are set, upload the reference documents Claude needs to actually do the job well. Continue to Lesson 08.