PennyweightPennyweight

Connect Pennyweight to Gemini

Last updated October 9, 2026

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Connect Gemini once and it can work with your Pennyweight data in any chat where you call on it. Before you start, read Connect your AI and turn on two-factor: Pennyweight refuses to authorize an AI until two-factor is on.

Before you start

Per Google's help center, custom apps in Gemini need all of these: you're 18 or over and in the US, you sign in with a personal Google Account (work and school accounts aren't supported yet), and Keep Activity is on. Custom apps are English-only for now. If you don't see the option below, one of these is usually why.

How to do it in the Gemini app

You add a custom app on the web. After that it also works in the Gemini mobile app.

  1. On a computer, go to gemini.google.com.
  2. Click Settings, then Connected Apps. If you don't see Connected Apps, click Personal Intelligence first.
  3. Under Custom apps, click Add a custom app.
  4. Enter this URL: . Click Next and follow the on-screen steps.
  5. When Gemini sends you to Pennyweight, sign in if asked, enter your passphrase and click Authorize. Pennyweight sends you back to Gemini.
  6. In a chat, type @ and pick Pennyweight so Gemini uses it.

Google's steps can change. If a label differs, check Google's help page for custom apps.

How to do it in the Gemini CLI

  1. Add the server:
  2. Or add it by hand to ~/.gemini/settings.json: under mcpServers, add an entry named pennyweight with httpUrl set to .
  3. Run gemini, then /mcp auth pennyweight. Your browser opens: sign in to Pennyweight, enter your passphrase and click Authorize.

The CLI also notices on its own that Pennyweight needs sign-in, because Pennyweight answers an unsigned request with a pointer to its sign-in. Run /mcp to see the server's status. The browser step doesn't work over SSH without a display or in a container without a browser, per the Gemini CLI docs.

Check the connection

Once you're connected, ask:

Try asking

Are you connected to Pennyweight? List my accounts.

What you'll see

Your AI calls Pennyweight and lists your accounts by name with their current balances. Next, try your first conversation.

Good to know

  • Google says Gemini asks you to confirm before a custom app makes changes.
  • Pennyweight accepts sign-in callbacks from gemini.google.com and google.com, and from localhost addresses, which is what the CLI uses.
  • The authorization page shows which Pennyweight account you're granting, and asks for your passphrase every time you connect.
  • If two-factor is off, the page tells you to set it up in Settings → Security and retry. For other errors, see Can't authorize your AI.
  • The grant lasts 30 days of active use. You can revoke it at any time from Settings → Connect your AI; see manage and revoke AI access.
  • Gemini never gets your passphrase or encryption keys. It gets an opaque token that lets Pennyweight's server decrypt your data for tool calls only.
  • If Gemini won't authorize, remove Pennyweight and add it again.
  • Connect your AIAdd Pennyweight to Claude, ChatGPT, Gemini or Grok with one link, then authorize it with your passphrase. How connecting works and where each guide lives.
  • Turn on two-factor authentication (and why it's required)Turn on two-factor in Settings before you connect a bank or authorize your AI. Here is where to find it and what changes if you turn it off.
  • Can't authorize your AIThe Pennyweight page that approves your AI stopped you with a message. Here is what each message means and how to get the connection through.
  • Your first conversation with PennyweightA hands-on first session. Your AI looks over your accounts, sorts out uncategorized spending, makes a rule and sets a first budget.