Claude Projects is a persistent workspace inside Claude.ai (included with Claude Pro at $20/month, one project available on the free plan) where you upload business documents and write a custom system prompt once. Every new conversation in that project then reads your files and instructions automatically, so Claude already knows your brand voice, services, and audience without re-explaining.
What you will be able to do
- Create a named Claude Project workspace scoped to one specific use case, like content creation or client onboarding, instead of a generic catch-all.
- Upload 2-3 business documents (brand voice guide, service descriptions, frameworks, audience notes) so Claude reads them before every response.
- Write a custom system prompt with CONTEXT, TONE, OUTPUT FORMAT, and WHAT TO AVOID sections that define Claude's role in that Project.
- Test the assistant with prompts that check whether it cites your uploaded documents and stays on-brand without being reminded.
- Diagnose and fix common failures, such as Claude ignoring your documents or drifting off-brand, using the troubleshooting fixes in this lesson.
Before you start
- A Claude Pro subscription ($20/month) for full Projects access, or the free plan, which allows one Project.
- 2-3 existing business documents ready to upload (brand voice guide, service descriptions, frameworks, audience research, or an intake questionnaire) in TXT, PDF, DOC, DOCX, or Markdown format.
- Awareness of the 200K token per-project limit (roughly 150,000 words) so you choose documents you reference constantly rather than uploading everything.
Reference
| Step | Action | Detail |
|---|---|---|
| 1. Create workspace | Click "Projects" in the left sidebar, then "+ New Project" | Name it for the specific use case (e.g. "Content Creation Assistant"), not "My Project" |
| 2. Upload context | Click "Add content" in the Project header | Upload 2-3 key documents; 200K token limit per Project (about 150,000 words); supported formats: TXT, PDF, DOC, DOCX, Markdown |
| 3. Write system prompt | Click the settings gear, then "Set custom instructions" | Structure it around four sections: CONTEXT, TONE, OUTPUT FORMAT, WHAT TO AVOID |
| 4. Test | Start "New Chat" inside the Project | Ask a business-specific question without naming your uploaded documents; check if Claude cites them on its own |
| Pricing | Claude Pro plan | $20/month, Projects included; free plan allows one Project |
Common errors and fixes
| Problem | Fix |
|---|---|
| Claude ignores your uploaded documents | Add an explicit line to the system prompt: always review uploaded documents before responding, and cite which document was used and quote the relevant section |
| Responses don't match your brand voice | Rewrite the brand voice guide to be more specific, for example "write like explaining to a smart friend over coffee, use contractions, keep sentences short, no corporate jargon" instead of vague terms like "friendly and professional" |
| Claude forgets context mid conversation | The lesson attributes this to likely hitting the Project's context window limit, which is also why it recommends keeping uploads to 2-3 focused documents within the 200K token limit rather than uploading everything |
| Test conversation feels generic or off-brand overall | Edit the system prompt to be more specific about what you want, then rerun the test prompts and check for document citations and consistent tone |
Read the full walkthrough
The complete lesson, with screenshots and any downloads, is published on Substack as part of Claude Systems Masterclass.
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