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Use Small from Claude or ChatGPT

Connect Small to the assistant you already use, then ask it to do the invoicing: draft an invoice, bill a project’s hours, check who hasn’t paid. It asks you before it sends anything. Connecting is free on every plan.

Connect it in a minute

Every assistant needs the same address:

https://app.smallpay.co/mcp

Claude

  1. In claude.ai, open Settings, then Connectors.
  2. Choose Add custom connector and paste the address above.
  3. Sign in to Small, pick your business, and press Allow.

ChatGPT

  1. In ChatGPT’s settings, find Apps & Connectors and turn on developer mode.
  2. Create a connector with the address above, signing in with OAuth. If it asks for a type, choose Streamable HTTP, not STDIO.
  3. Sign in to Small, pick your business, and press Allow.

Claude Code

  1. Make an API key in Small under Settings → API keys. Keys are part of Pro.
  2. Run this, with your key in place of the placeholder:
  3. claude mcp add --transport http small \
  https://app.smallpay.co/mcp \
  --header "Authorization: Bearer <your key>"

Menus move. If a step reads differently, look for adding a custom or remote MCP connector, of the Streamable HTTP type. Any assistant that supports those can connect the same way.

Things to ask

Say it the way you would to a person. It knows your clients, projects, rates and hours.

  • “Bill Harbourside Cafe for October's hours.”
  • “Which invoices are overdue, and by how much?”
  • “Log three hours on the kitchen refit for yesterday.”
  • “Invoice Northwind for the same as last month.”
  • “Draft an estimate for a 12-week retainer at $2,000 a month.”
  • “Who owes me the most right now?”

What it can and can’t do

It can

  • Read your invoices, estimates, clients, projects and time.
  • Draft and change invoices and estimates, and add clients and projects.
  • Log time and put unbilled hours on an invoice.
  • Send an invoice or estimate to your client, once you’ve said yes. Sending can’t be undone, so it checks with you first.

It can’t

  • Void or refund an invoice, or mark one paid.
  • Delete invoices, clients, projects or tasks.
  • See anything in a business you didn’t connect it to.
  • Change anything if your seat is read-only.

Those are done in Small itself. You can disconnect an assistant at any time under Settings → Connected apps, and it stops working straight away.

Start free, then connect your assistant.

Connecting is free on every plan. See pricing for everything else.

Start invoicing free