Connect Pennyweight to Gemini

Gemini can connect to Pennyweight as a custom app. You add it once in the Gemini web app by pasting Pennyweight’s server URL, and then it works in Gemini on the web and on your phone.

Before you start

Google limits custom apps to accounts that meet all of these: you’re 18 or over and in the US, signed in with a personal Google Account(the feature isn’t available on a work or school account), with Keep Activity turned on. The feature is English-only for now. If you don’t see the option below, one of these is usually why.

Add Pennyweight in the Gemini app

• On a computer, go to gemini.google.com and open Settings → Connected Apps. You have to connect a custom app on the web — you can’t add one from the mobile app.
• Under Custom apps, choose Add a custom app and enter the Pennyweight server URL: https://mcp.pennyweight.ai. Click Next.
• Complete the sign-in: Gemini sends you to Pennyweight to sign in, complete two-factor, and enter your passphrase. That handshake binds the connection to your account.
• In a chat, type @and pick Pennyweight to use it, then ask your first question. Once connected it’s available in the Gemini mobile app too.

The command-line alternative

If you’re comfortable with a terminal, the Gemini CLI also supports remote MCP servers with sign-in. Add Pennyweight to your ~/.gemini/settings.json:

• Under mcpServers, add an entry named pennyweight with "httpUrl": https://mcp.pennyweight.ai and an "oauth": { "enabled": true } block.
• Run gemini, then use the /mcp command to see the connection and /mcp auth pennyweight to sign in (it opens your browser; complete two-factor and your passphrase).

Heads-up: a Google transition is underway

Google is moving Gemini CLI users to a new tool called Antigravity CLI. If your Gemini CLI stops working, check Antigravity’s own documentation for how it wants remote MCP servers configured — the idea is the same, but don’t assume the config fields match. The Gemini app steps above are unaffected.