CLAUDE.md and memory — making Cowork remember

TL;DR. Give Cowork two layers of memory. CLAUDE.md is a markdown file you control; it lives in the workspace, you read it, you edit it, the team sees it. Memory is Anthropic's automatic recall across sessions, useful for evolving operational knowledge. Use both. CLAUDE.md is the contract; Memory is the notebook.

The two layers#

CLAUDE.md is a file you control. It lives in the workspace folder, you can read it, you can edit it, and Cowork loads it at the start of every session. It is the team's standing agreement with the model — house style, file naming, rules, things never to do.

Memory is Anthropic's feature that lets Cowork accumulate facts across sessions automatically. You can read and edit memory entries inside the app, but they live in the app, not in a file you can commit alongside your work.

Both work together. CLAUDE.md is for stable house rules everyone shares; Memory is for evolving operational knowledge that may only matter to one operator. CLAUDE.md is the contract; Memory is the notebook.

What goes in CLAUDE.md#

Concrete sections that should appear in every team's CLAUDE.md:

• Identity — who is using this workspace, for what function, how to reach the owner.
• House style — voice (e.g., "British English, no em-dashes, no marketing language"), formats (Word over PDF for drafts; Excel always with column headers), naming convention.
• Operational defaults — currency, date format, timezone, fiscal year.
• Allowed and forbidden actions — "never delete files in archive/", "never overwrite anything in /clients/ — always create v2".
• Prompt templates — saved prompts the team uses repeatedly.
• People and roles — who approves what.
• Last updated date and editor.

Length: 100–300 lines is healthy. Over 500 starts to dilute — Cowork still reads it but the most important rules get less weight.

A real CLAUDE.md skeleton (copy-paste)#

# CLAUDE.md — Finance Workspace

Owner: Sarah K. · Last updated: 2026-04-20

## Identity
This workspace is for the FP&A team at [Company].
Operators: Sarah, Jorge, Priya.

## House style
- British English, no em-dashes, no marketing language.
- Currency: GBP unless explicitly USD or EUR. Always show the
  currency code, never the symbol alone.
- Date format: 25 Apr 2026 (no slashes).
- Excel: column headers in row 1, no merged cells, freeze top row.

## Operational defaults
- Fiscal year ends 31 March.
- Reporting timezone: Europe/London.

## Allowed / forbidden
- Never delete or overwrite anything inside /archive/.
- Always create v2, v3, etc. for files in /clients/ — never overwrite v1.
- For invoice extraction, always cite the source page in the output.

## Saved prompts
### Close-pack summary
Take all files in /inbox/close-[month] and produce a 5-page
close-pack summary...

### Variance explainer
Compare /inbox/budget.xlsx and /inbox/actual.xlsx...

## People
- Sarah: pilot owner, approves new prompt templates
- Jorge: AP focus
- Priya: AR focus

Steal it. Adapt the names. Ship.

What Memory is good for#

• Names, definitions, and reusable preferences. "Acme is our largest customer; their fiscal year ends Dec 31."
• "Don't ask me again." Small operator preferences that don't deserve a CLAUDE.md edit.
• Recurring task notes. "Last month's close had a tax accrual issue — flag if I see similar this month."

Memory shines when the fact is one operator's, not the team's, and when it might evolve quickly enough that a CLAUDE.md edit would be overhead.

What Memory is not good for#

• Sensitive data. Do not ask Cowork to "remember" passwords, PII, or anything you would not write on a sticky note on a shared monitor.
• Stable house rules. Those go in CLAUDE.md so they are visible to the team and version-controlled.
• Anything you want to revoke cleanly. Memory entries can be deleted, but you have to know what is there to delete it.

If you find yourself relying heavily on Memory for something, that's a signal it should probably move to CLAUDE.md.

Memory hygiene#

A short monthly routine:

• Open Memory settings; review entries; prune anything stale.
• Promote anything used by more than one operator into CLAUDE.md.
• Demote anything in CLAUDE.md that turned out to be only one person's preference.

This takes ten minutes and prevents the slow drift where CLAUDE.md and Memory diverge from the team's actual practice.

CLAUDE.md and Code together#

If your team uses both Cowork and Claude Code, the same CLAUDE.md works for both. Engineers and operators sharing one file is the cheapest single source of truth you will ever build. The voice rules apply uniformly; the forbidden actions apply uniformly; the saved prompts can be tagged so each tab picks the right ones. See Cowork vs Chat vs Code for the cross-tab patterns.

Tinkso's take#

CLAUDE.md is the second deliverable in every Tinkso engagement, after the workspace structure. We co-write it with the pilot team during the Co-design beat — not in a back room. The file the team co-wrote is the file they will defend.

We treat CLAUDE.md as a living document. Version it in the cloud sync alongside the workspace; review it monthly; retire entries that no longer apply. The teams that lose to AI are the ones whose CLAUDE.md still reflects what they thought in week one of last year.

Try this#

Open your workspace's CLAUDE.md. If it is empty, paste the skeleton above and adapt it. If it is not empty, scan for one specific thing: do you have at least one forbidden action rule? If not, add one. That is the most underused section, and it is the one that prevents the most regret.