Using a Grok skill for supplier invoices

The example: a small engineering workshop

Consider the fictional engineering workshop Wattle Creek Engineering:

• Business: Wattle Creek Engineering
• Type: steel fabrication and repair workshop
• Size: 8 staff, with one admin, Sam
• Customers: builders, farms and local councils
• What they provide: custom steel frames, brackets and gates, plus on site repairs

We're going to focus on Sam, the admin from Wattle Creek Engineering, who uses Grok to sort the inbox and send invoices from THE SUPPLIER, Southside Steel, on to Hubdoc, but still checks every invoice by hand before it reaches Xero.

Here are the people and tools involved.

Workflow today

This is how Sam handles supplier invoices today.

Grok already helps Sam at the start and the end. Everything in between is manual. Sam checks every invoice in Hubdoc, spots the odd ones and approves each one in Xero.

Grok can take on more of the checking. With Grok connected to the admin inbox and a gateway to Xero, a Grok skill can read each invoice as it arrives, create a coded draft in Xero and flag only the odd ones, so Sam only looks at what needs a decision. Here is the same workflow with those changes in place.

Setting it up

Grok has no connector for Xero, and Xero's own AI connector is built for Claude and is read only. So the setup adds a small program of your own, called a gateway, between Grok and Xero.

There are four pieces. Grok connects to the admin inbox and to the gateway. The gateway runs on a computer in the office and holds the key to Xero. A skill tells Grok what to do with each invoice, and an Automation runs it without Sam asking.

The gateway sits on an office computer, not on someone else's server, so the Xero key never leaves the office. Grok runs on xAI's servers, so it reaches the gateway through a locked tunnel.

What a skill is

A skill is a set of saved instructions Grok follows every time it does one job. Sam writes it once, in plain words, and Grok uses it on every invoice that comes in.

Grok has a built in Skill Creator that writes the skill with you. You describe the job, it asks questions, and it saves the result. You can edit the skill later as the rules change.

For this job, the skill says which emails are supplier invoices, where to look up each supplier's usual account and GST in Xero, and when to stop and flag an invoice for Sam.

Work through the steps below in order. Each one builds on the one before.

A starting skill you can adapt

Download the skill template as a text file. Fill in your suppliers, then paste it into the Skill Creator. It covers the same points as the list below.

Or open the Skill Creator and describe the job in plain words, with your own supplier names:

• Name: Supplier invoices to Xero.
• Job: read admin inbox emails since the last run that look like supplier invoices.
• Not an invoice (statements, remittances, quotes, order confirmations): apply the right label (Gmail) or move to the right folder (Outlook).
• For each invoice: find the supplier in Xero, look at their last few invoices for the usual account and GST, and create a draft invoice coded the same way.
• Flag, do not act: a supplier not in Xero, a credit note, an amount well above usual, an invoice number already in Xero, or any change to a supplier's bank details.
• Never approve, pay or delete anything in Xero.
• Finish with one list of the drafts created, what was flagged, and why.

The bank details line matters most. Scammers change the account number on a real looking invoice, and a coded draft will not show it.

Caveats

• It takes some setting up. Steps 2 to 5 need someone comfortable with keys, a bridge program and a tunnel. This is the part most businesses get help with.
• Why the gateway stays local. The Xero key never leaves the office computer. What Grok can do is limited by three things, the tunnel's sign in, the tools switched on in the gateway, and the access ticked in Xero. Read the gateway's log each week for the first month.
• The office computer has to be on. If it is asleep when the Automation runs, nothing reaches Xero. Those invoices wait for the next run.
• Keep a person on the money. Sam still approves every invoice and makes every payment. A change to a supplier's bank details always gets a phone call, on a number you already hold.
• Grok can still get it wrong. It can misread an amount or pick the wrong account. That is why everything lands as a draft. Spot check the drafts for the first few weeks.
• Not yet confirmed by xAI. Its docs do not say whether custom connectors work inside Automations, whether an Automation can make changes without someone approving them, or which sign in methods custom connectors accept. Test all three before you rely on the Automation. Until then, run the skill by hand.
• Hubdoc and duplicates. Once Grok creates drafts for a supplier, stop sending that supplier's invoices to Hubdoc, or they reach Xero twice.
• Costs. A Xero Custom Connection is about A$10 a month. Email triggers need SuperGrok, and custom connectors may need a paid Grok plan. xAI's announcement does not say which plans include Skills, so check at grok.com/skills.
• Your data. Invoices carry bank details and prices. Look at Grok's data settings before you connect the admin inbox.

If this is too much

There is a simpler route with no gateway and no tunnel. Mail rules forward invoices to Hubdoc, Hubdoc's supplier rules code them, and Grok flags the odd ones. It does less, but there is nothing to run. Read the simpler route.

Xero is building the same thing in

In September 2026 Xero renamed Files to Documents and put Smart Document Capture there (Xero's post).

Xero says a forwarding address and supplier rules are coming "in the coming months". Creating invoices straight into awaiting approval is further out.

Check Xero's Documents area each quarter. Once it can do this job itself, the gateway is no longer needed.