Claude Projects and Custom Instructions

One of Claude's most powerful features is Projects — a way to give Claude persistent context so it understands your work without you having to repeat yourself in every conversation. This lesson shows you how to set up and use Projects effectively.

What Are Claude Projects?

A Project is a dedicated workspace in Claude where you can:

• Upload reference documents that Claude can access in every conversation within that project
• Set custom instructions that define how Claude should behave
• Organize conversations by topic or purpose
• Share with team members (on Team and Enterprise plans)

Think of a Project as giving Claude a "briefing" before it starts helping you. Instead of explaining your company, your writing style, or your technical stack in every new chat, you set it up once and Claude remembers.

Creating Your First Project

Step 1: Navigate to Projects

On claude.ai, click on Projects in the left sidebar. Then click Create Project.

Step 2: Name and Describe Your Project

Give your project a clear name and description:

• Name: "Q1 Marketing Campaign" or "Backend API Development"
• Description: A brief summary of what this project covers

Step 3: Add Custom Instructions

This is where Projects become powerful. Custom instructions tell Claude how to behave in every conversation within this project.

Example for a writing project:

You are helping me write blog posts for my tech startup's blog.

Key guidelines:
- Our audience is small business owners, not developers
- Use simple language, avoid jargon
- Keep paragraphs short (2-3 sentences)
- Include practical examples and actionable advice
- Our brand voice is friendly and authoritative, not salesy
- Always suggest a call-to-action at the end of each post

Example for a development project:

You are helping me develop a Next.js application with TypeScript.

Technical context:
- We use Next.js 15 with the App Router
- Database: Supabase (PostgreSQL)
- Styling: Tailwind CSS
- State management: React Context + hooks
- Testing: Jest + React Testing Library

Coding guidelines:
- Use TypeScript strict mode
- Prefer server components where possible
- Follow the existing patterns in the codebase
- Include error handling in all async functions

Step 4: Upload Knowledge Files

Upload documents that Claude should reference:

• Brand guidelines — Style guide, tone of voice document
• Technical docs — API documentation, architecture diagrams
• Reference materials — Research papers, competitor analysis
• Code files — Existing codebase, configuration files
• Data files — CSV files, product catalogs, pricing sheets

Claude can reference these files in any conversation within the project.

Custom Instructions Deep Dive

Custom instructions are the most impactful part of Projects. Here's how to write effective ones:

Structure Your Instructions

A good set of custom instructions covers:

1. Role — What Claude should act as
2. Context — Background information about the project
3. Guidelines — Rules and preferences to follow
4. Format — How to structure responses
5. Constraints — What to avoid

Example: Content Writer Instructions

Role: You are a senior content writer for FreshEats,
a meal kit delivery service.

Context:
- We serve health-conscious professionals ages 25-45
- We differentiate on organic ingredients and 20-minute recipes
- Our competitors are HelloFresh, Blue Apron, and Home Chef
- We're positioned as premium but accessible

Guidelines:
- Lead with benefits, not features
- Use sensory language when describing food
- Include nutritional highlights naturally (don't make it clinical)
- Reference real cooking scenarios ("after a long workday...")
- Keep sentences under 20 words when possible

Format:
- Blog posts: 800-1200 words with H2 subheadings every 200 words
- Social posts: Under 150 characters with one emoji maximum
- Email: Subject line + 3 short paragraphs + CTA button text

Avoid:
- Comparing directly to competitors by name
- Making health claims we can't substantiate
- Using the word "delicious" (overused in food marketing)

Example: Code Review Instructions

Role: You are a senior developer reviewing code for our team.

Context:
- TypeScript/Node.js backend with PostgreSQL
- We follow the Airbnb style guide
- Performance matters — this serves 10K requests/second

When reviewing code:
1. Check for security vulnerabilities first
2. Look for performance issues
3. Verify error handling is complete
4. Suggest cleaner patterns if applicable
5. Note any missing tests

Response format:
- Start with a severity summary (critical/warning/suggestion counts)
- List issues by severity
- Include code snippets showing the fix
- End with overall assessment

Managing Knowledge Files

What to Upload

Knowledge files work best when they're:

• Text-based — PDFs, documents, code files, CSVs
• Well-structured — Clear headings and sections
• Relevant — Directly related to the project's purpose
• Current — Up-to-date information

File Size Limits

Projects have a total knowledge base limit. To make the most of it:

• Upload the most important documents first
• Summarize very long documents before uploading
• Remove outdated files when you update them
• Use text files instead of heavily formatted PDFs when possible

Organizing Files

Name your files clearly so Claude (and you) can reference them:

• brand-guidelines-2026.pdf — not doc1.pdf
• api-endpoints.md — not notes.md
• q1-sales-data.csv — not data.csv

Project Ideas

Here are practical projects to get started:

Personal Writing Assistant

• Instructions: Your writing style preferences, audience, topics you cover
• Knowledge: Previous articles, style guide, audience research
• Use for: Blog posts, newsletters, social media content

Study Companion

• Instructions: Your course details, learning goals, preferred explanation style
• Knowledge: Syllabus, textbook chapters, lecture notes
• Use for: Reviewing concepts, practice questions, essay planning

Business Analyst

• Instructions: Company context, industry details, reporting preferences
• Knowledge: Financial data, competitor reports, market research
• Use for: Analysis, reports, strategic recommendations

Job Search Helper

• Instructions: Your experience, target roles, industries of interest
• Knowledge: Your resume, job descriptions, company research
• Use for: Resume tailoring, cover letters, interview prep

Tips for Getting the Most from Projects

Be Specific in Instructions

Too vague:

Be helpful and write good content.

Much better:

Write in active voice, keep paragraphs under 4 sentences,
and always include at least one specific example per section.

Update Instructions as You Learn

Your first set of instructions won't be perfect. After a few conversations, you'll notice patterns in how you correct Claude. Add those corrections to your instructions:

"I keep asking Claude to shorten its responses → Add 'Keep responses concise — aim for the shortest answer that's still complete.'"

Use Multiple Projects

Don't put everything in one project. Create separate projects for different purposes:

• One for blog writing
• One for code development
• One for business analysis
• One for personal tasks

Each project's instructions and knowledge files stay focused and relevant.

Key Takeaways

• Projects give Claude persistent context so you don't repeat yourself in every conversation
• Custom instructions define Claude's role, guidelines, format, and constraints for a project
• Upload knowledge files (documents, code, data) that Claude can reference across conversations
• Structure your instructions clearly with role, context, guidelines, format, and things to avoid
• Create separate projects for different purposes to keep context focused
• Update your instructions over time as you learn what corrections you keep making