Connect Claude, ChatGPT, or Gemini to your Foundry game.

Which AI assistants can drive Foundry?

Claude, ChatGPT through Codex, and Gemini through Antigravity can all drive Foundry. They connect over MCP, the Model Context Protocol, an open standard that lets an AI app reach an outside tool and use it. Familiar is that tool: it exposes your Foundry table so a connected assistant can read the world and run it.

Think of MCP as a universal plug. Each AI app used to need its own custom wire to each tool. MCP is the one shape they all agree on, so any assistant that speaks it connects to Familiar without bespoke wiring.

The draw is the bill. Built-in chat runs on an API key you top up per token. MCP runs on the subscription you already hold, so no second invoice arrives.

Honest about the limit: MCP spends your normal subscription quota. A long, heavy night can still hit your plan's rate limits, the same as any other use of that app.

What do you need before you connect?

Three pieces, and you likely have two already.

• Foundry VTT on v13 or later, with a world you run as GM.
• Familiar installed and enabled in that world. If you have not installed it yet, search for it in Foundry's package browser or paste the manifest URL, both through the Install Module dialog.
• A desktop AI app on a plan that supports MCP connectors: Claude, ChatGPT through Codex, or Antigravity for a Google account. Check that your plan exposes the connector feature.

• Install Familiar in Foundry
• New to Familiar? Start with adding AI to Foundry

How do you connect Claude or ChatGPT to Foundry?

You connect in three steps: add Familiar as a connector in your AI app, let the wizard write the config, then authorise the link and send a test message.

The exact clicks shift with each app version, so treat this as the shape, not a script. Familiar ships an MCP Setup Wizard that detects your client and generates the config for you, which is the part that saves the fiddly work.

You meet the word MCP in two places: your assistant's connector settings, and Familiar's own MCP / Subs tab in Foundry, where the wizard lives.

1. 1

   Add Familiar as a connector

   Open where your AI app manages MCP servers and add one for Familiar. That is the handshake that lets it see the tools your Foundry world exposes.

2. 2

   Point it at your world

   Familiar runs a small local server next to Foundry, started with npx familiar-vtt. The wizard generates the exact config, secret included, so you paste rather than hand-edit.

3. 3

   Authorise and confirm

   Approve the connection, send a test message, and once the assistant sees the Familiar tools you are ready to run.

Menu names and field labels move between app versions, so steps printed here would go stale. For the current click-by-click, go to the install link, the Discord, and the Familiar docs.

Pick your assistant

The clients group by the assistant behind them. Claude runs on Anthropic, your ChatGPT plan connects through Codex, and Gemini through Google's Antigravity.

For OpenAI you connect through Codex, the assistant your ChatGPT Plus, Pro, or Team plan includes; there is no separate ChatGPT app to wire up. For Gemini there is no standalone Gemini app either. Reach it through Antigravity, Google's own agent you sign into with a Google account, or paste a Google API key into the built-in chat to run a Gemini model directly.

Leave FAMILIAR_WS_SECRET as the placeholder. The wizard generates the real secret and fills it in, so the safe move is to copy the finished command straight from the wizard.

claude mcp add --scope user --env FAMILIAR_WS_SECRET=<your-secret> familiar -- npx familiar-vtt

codex mcp add familiar --env FAMILIAR_WS_SECRET=<your-secret> -- npx -y familiar-vtt

• Playing D&D with Claude, the full path
• Playing D&D with ChatGPT through Codex
• Playing D&D with Gemini through Antigravity
• Choosing an AI model, and how hard it thinks

How does it feel at the table?

You talk to your AI app in plain language, the same as always, and it runs your table through Familiar.

Ask it to set the scene, run the next fight, or remind you what the innkeeper knew. It reads the situation, calls the Familiar tools in Foundry, and the canvas updates: tokens move, conditions apply, the journal opens to the right page.

One thing to know up front. When you ask for voice or a scene change, the audio plays and the canvas changes in your Foundry browser tab, not inside the AI app, which gets a short text confirmation. Generated images are the exception: they come back inline, so an image-capable client can show them. A handful of in-Foundry chat features stay in the built-in window and are not reachable over MCP: live transcription, auto-pilot for NPC turns (D&D 5e), automatic memory and knowledge-base context, slash commands, and drag-and-drop attachments.

• Combat & AI
• Journals & Notes
• Characters & Items
• Knowledge & Memory

Fixing a connection that will not take

Most connection problems come down to three things: the browser, a hosted Foundry, or the local server.

• Safari blocks this kind of local connection. Use Chrome, Edge, or Firefox.
• Hosted Foundry works. Hosts like The Forge are fine, because the MCP server runs on your own computer and your browser connects to it locally, so the host is never in the path. Run the wizard from your hosted game and it bakes in your game's URL for you.
• If a paste does not take, the secret is usually wrong or the local server is not running. Recopy the finished command from the wizard, check that npx familiar-vtt is running, and try again.

• Stuck? Ask in the Discord

Connect the AI you already use

If Familiar is already in your world, connecting is a short job: add it as a connector, let the wizard generate the config, authorise the link, and send a test message. From there you run your game from the assistant you know.

Install Familiar in Foundry to get started, and keep the install link or the Familiar docs alongside for the current click-by-click steps.

• Install Familiar in Foundry
• The rules I give my AI DM