How to set up CosBooks: your books in Claude in about ten minutes

Setting up accounting software is usually the part where people quit. This one is short, because there are no screens to configure — most of the setup is a conversation, and the parts that are not take about two minutes.

Here is the whole path: create an organization, connect it to Claude, tell it what you own and owe, then work.

Step 1 — Create your organization

Sign up with your email, your name and your company name. Behind the signup, CosBooks provisions a dedicated organization: a Postgres schema of your own, a seeded chart of accounts with 40+ standard accounts, and an owner membership for you.

The dashboard you land on is deliberately small. It handles account housekeeping — connection details, API keys, company settings — and nothing else. All the accounting happens in Claude.

Step 2 — Add the connector in Claude

This is the only genuinely technical step, and it is four clicks.

1. 01

   Open connector settings

   In Claude, go to Settings → Connectors → Add custom connector.

2. 02

   Paste your MCP endpoint

   Copy the endpoint from the Connect page of your CosBooks dashboard — it looks like https://your-host/mcp — and paste it in.

3. 03

   Sign in and authorize

   Claude opens a sign-in page. Use the same email and password as the dashboard, then choose which organization to grant access to. CosBooks uses OAuth 2.1 with PKCE, so no password or key is ever pasted into a chat.

4. 04

   Confirm the tools loaded

   Ask “what accounting tools do you have?” Claude should list invoices, bills, payments, reports, banking and more. If it does, you are done — the connector works on web, desktop and mobile from here.

If you are a developer who would rather run the server locally, generate an API key under Settings → API Keys and point a stdio MCP entry at your own build instead:

{
  "mcpServers": {
    "cosbooks": {
      "command": "node",
      "args": ["dist/index.js"],
      "env": {
        "SUPABASE_DB_URL": "postgresql://...",
        "COSBOOKS_API_KEY": "cb_live_..."
      }
    }
  }
}

API keys are shown once, scoped to a single organization, and revocable from the dashboard. Treat one like a password: if a laptop goes missing, revoke the key rather than changing anything else.

Step 3 — Shape your chart of accounts

The seeded chart is a reasonable general-purpose starting point, but five minutes of tailoring pays for itself every month afterwards. Ask for what your business actually spends money on:

• “Show me my chart of accounts.”
• “Add expense accounts for Contractors, Software Subscriptions and Client Travel.”
• “Rename Office Supplies to Studio Supplies.”
• “I don’t have inventory — hide the inventory accounts.”

A good rule: create an account when you would want to see that number on its own line in a P&L, and not before. Twelve well-chosen expense accounts beat forty precise ones you never look at.

Step 4 — Enter opening balances

This is the step people skip, and it is the one that determines whether your reports mean anything. Pick a start date — the first day of a month or quarter — and tell Claude the position of the business on that date.

• Bank and cash balances as of the start date, from the statement rather than from memory.
• Unpaid customer invoices you are still owed, with their original dates and due dates.
• Unpaid bills you still owe.
• Loans, credit cards and other liabilities, at their balance on the date.
• Fixed assets you already own, with what you paid and when.

Say it in a sentence and let the ledger do the bookkeeping: “As of March 1st I had $18,400 in checking, $2,150 on the business credit card, and Widget Co owes me $4,500 on an invoice dated February 10th.” CosBooks posts a balanced opening entry with the difference going to opening balance equity.

Then verify. Ask for a trial balance and a balance sheet as of the start date and read them. If the bank number does not match your statement, fix it now — before a hundred transactions sit on top of it.

Step 5 — Connect the flow of money

With a starting position in place, two habits keep the books current.

Record as you go

Invoice from wherever you are, the moment the work is done. “Invoice Northwind for the April retainer, $3,000, net 15.” Record payments as they land. “Northwind paid $3,000 today.” Both post immediately, so your AR is never a guess.

Import and reconcile monthly

Export a CSV from your bank, import it, and work the matches. Transactions that correspond to invoices or bills already in the ledger get matched; the rest get categorized, and each categorization you confirm becomes a rule that handles the same merchant automatically next month. The first import is the slow one. By the third, most of a statement categorizes itself.

Step 6 — Run your first close

At month end, ask for the monthly close. It is a guided sequence rather than a single report:

1. Reconcile every bank and credit card account against its statement.
2. Review uncategorized transactions and anything flagged as unusual.
3. Check AR and AP aging for anything that has drifted past terms.
4. Read the P&L and balance sheet, and ask about anything that looks off.
5. Compare against budget if you set one.

The first close takes an hour and teaches you where your data is messy. The fourth takes fifteen minutes. That trajectory is the entire point.

Things worth knowing early

• Voids reverse, they do not delete. Correcting a mistake leaves both the original entry and its reversal in the audit trail. That is a feature — your accountant needs to see the correction, not a gap.
• Roles are enforced server-side. A viewer connection cannot write to the ledger no matter how the request is phrased. Give an outside accountant a viewer role and they can read everything and change nothing.
• Ask before you assume. “Which account should a Stripe fee go to?” costs one sentence and prevents a reclassification later.
• The dashboard is not the product. If you find yourself hunting for a screen to do something in, ask Claude instead — the tool surface is much wider than the dashboard.

A first-week checklist

1. Organization created and connector added in Claude.
2. Chart of accounts reviewed and tailored to your business.
3. Opening balances entered and verified against a trial balance.
4. One real invoice created and one real payment recorded.
5. One bank statement imported and reconciled to zero.
6. A P&L and balance sheet read end to end, with every surprising line asked about.

Work through that and the books are live. If you want the mechanics underneath — how a sentence becomes balanced journal entries — read how CosBooks works. If you are still deciding whether it fits your situation, who it is for is the more useful page.