How to Add Context to Claude

What counts as useful context?

Context includes the material Claude should work from and the circumstances that give it meaning. A spreadsheet needs a date range, units and an explanation of its columns. A complaint needs the actual complaint and the relevant approved policy. A speech needs to know who is in the room.

I would write a short source note before uploading anything: “This is the approved service list dated [date]. Use it for current descriptions. The attached newsletter is an old style example only.” That small distinction can prevent an impressive amount of nonsense.

Chat box: + → Add files or photos → Choose and attach the file → Ask Claude what it can read

How do you upload files to Claude?

In the chat composer, select +, then Add files or photos, choose the file and attach it. Dragging a file into the chat is another option. Claude’s upload guide lists supported formats and current limits.

After attaching the file, name the task and ask for an inventory of the material it can use. Start with a passage or figure you can check. Do this before requesting the full report.

Documents can contain information Claude does not extract in the way you expect. Check diagrams and embedded images separately; non-PDF document processing extracts text rather than interpreting their embedded images. A file appearing in the chat is the beginning of the check.

Chat attachment, Project or Connector: which should you use?

Choose the route that fits the information. Re-uploading a static policy can be entirely sensible. Building an integration for a single paragraph may be taking the scenic route.

Build a context pack Claude can actually use

For a fictional customer update, I would supply a current service sheet, a short audience brief and one approved writing example. I would leave out unrelated sales decks and old meeting notes.

Label the authority of each source

Say which document controls factual claims and which merely illustrates style. If two policies disagree, ask Claude to identify the conflict rather than choose silently. You still need the appropriate person to resolve it.

Define the terms people inside the business take for granted

Explain abbreviations, product names and whether “customer” means current clients or prospects. A tool cannot infer your office shorthand reliably just because everyone at the kettle understands it.

Before drafting, inventory the material available in this chat.
For each source, state its filename or label, date if shown, intended use and any access or extraction limitation you can identify.
Find the passage supporting [a fact you know is present]. Quote a short excerpt and give a page or section reference if available.
List conflicts and missing information. Do not draft yet.

What if the document or conversation is very long?

Give Claude a clear question and point to the relevant part. Break a complex review into stages: inventory, evidence table, analysis, then draft. Keep a short approved handover note containing the goal, decisions, unresolved questions and source versions.

If you begin a new chat, bring that note and the required sources with you. Do not rely on an old conversation being available in the precise way you expect. Project behaviour also varies between standard chat and the new beta described in the Projects guide.

More information is useful only when it improves the work. A filing cabinet emptied onto the floor has excellent coverage and terrible usability.

A practical exercise: give two sources different jobs

Use two fictional references. The current booking policy says: “Bookings can be changed up to 48 hours before the session.” An old newsletter says: “Change your booking any time before the morning of the session.” Label the first as current policy and the second as a style example.

Ask Claude which rule applies and where the references disagree. Then remove the authority labels and ask it to identify what needs resolving. The point is to see whether your context tells it which source controls the facts. A confident answer based on the older document is still the wrong answer.

Compare these fictional sources before drafting anything.
SOURCE A — current approved booking policy: Bookings can be changed up to 48 hours before the session.
SOURCE B — old newsletter, supplied for tone only: Change your booking any time before the morning of the session.
Identify the conflict, state which source controls the booking rule and explain how Source B may be used.
Then list what you would need to know if neither source had a date or authority label.

How To Use Claude Like A Pro: the six-part series

1. Part 1: How to Use Claude Projects Effectively
2. Part 2: How to Write the Best Claude Prompt
3. Part 3: How to Add Context to Claude (you are here)
4. Part 4: How to Add and Use Skills in Claude
5. Part 5: How to Add the Best MCPs in Claude
6. Part 6: How to Add Connectors in Claude

Start with our guide to using Claude effectively · See the full How To Use Claude Like A Pro series