Working With Your Own Files

The reason it is useful is the reason it needs care

Everything that makes Cowork worth using comes from the same fact: it works with your own files, folders and applications rather than with whatever you can be bothered to paste into a box. That is why it can produce something specific to your actual work instead of generic advice. It is also why this lesson exists.

Start with the easy half. Point it at a named folder rather than gesturing at your work in general. A named folder gives the job a boundary, makes the run reviewable, and means you know what was in scope when you check the result. My files is not a location. Northgate slash Q2 is.

What to keep away from it

This section matters more than the rest of the lesson, so read it slowly.

Client and customer data. Names, contact details, account numbers, case details, anything you hold because someone trusted you with it rather than because it is yours. The obligations attached to that material do not pause because a tool is convenient.

Anything covered by an employer policy or a signed agreement. Most organisations have rules about which systems may hold which information, and those rules apply to you whether or not you have read them. A non-disclosure agreement does not carve out an exception for tools you find helpful. If you do not know your organisation's position, that is the thing to resolve before you widen the folder, not after.

Anything you would not want summarised into another file. This is the test specific to this product and it deserves its own paragraph.

Why the summarised into another file test matters here

Pasting something into a chat window puts it in one conversation. Handing a folder to a job that produces output does something different: the material comes out the other side as new documents, sitting in your file system, now containing the sensitive parts in a fresh arrangement that no longer looks sensitive.

A summary of forty appraisal documents does not look like forty appraisal documents. It looks like a tidy one page summary. It is far more likely to get attached to an email, dropped into a shared folder, or reused six months later by someone who has no idea what it was distilled from. Anthropic is also unifying Claude chat and Cowork into one space with access to the same files, so the material and everything derived from it becomes reachable from more places, not fewer.

So the question is not only what am I comfortable handing over. It is what am I comfortable existing as a new document afterwards.

Anonymising is the middle path

The choice is rarely between handing over everything and handing over nothing. Most of the value in your material is in its shape, not in the identities attached to it. Patterns, counts, recurring complaints, timings and structures all survive anonymising completely intact.

Swap the identities out before the job starts, keep no mapping in the same place as the output, and you get the analysis without the exposure.

NEVER HAND OVER
client or customer records, case files, contact details
anything under an NDA or a confidentiality clause
pay, contracts, disciplinary or medical information
anything your employer's policy places off limits
anything you would not want to exist as a new tidy document
ASK FIRST
material belonging to a client rather than to you
anything that arrived from outside your organisation
anything where you do not know your organisation's position

REAL THING              REPLACE WITH
person's name           PERSON A, PERSON B
company name            CLIENT A, CLIENT B
account or case number  ACCOUNT 1, ACCOUNT 2
email address           CONTACT 1
exact salary figure     BAND 2
precise date of birth   AGE RANGE
full address            REGION
Keep the mapping somewhere separate from the output, or keep none at all.
Check free text as well as fields. Names hide inside complaint descriptions.

Use only the files in [named folder]. Do not read anything outside it,
including subfolders I have not named.
Before producing anything, replace all names, account numbers and
email addresses with placeholders. Do not reproduce them anywhere
in the output, including in examples and quotations.
Create your output as a single new file inside [named folder].
Do not create, rename, move or delete anything else.
Do not send, share or publish it.
Finish by listing which files you read, which you could not open,
and anything you assumed. Then wait for my approval.