Two parts: the connector lets Claude work with your YNAB plans, and the Skill tells Claude how to enter receipts, review imports, cover overspending, track reimbursements and tidy up. You need a Claude Pro plan or higher.
On claude.ai on a computer, go to Customize > Connectors and add a custom connector with this address:
https://ynab-mcp-sooty.vercel.app/mcp
Connect it, sign in with YNAB, and say who you are.
Sign in with the YNAB account you connected in step 1 to download it.
In Customize > Skills, upload the zip. Code execution must be on (Settings > Capabilities). Then send Claude a photo of a receipt in a chat with the connector on.