How to add AI to Foundry VTT
Install Familiar, activate your licence key, then paste a provider key or connect a plan you already pay for.
Guides
Running D&D with AI in Foundry VTT.
I built Familiar and run my own campaign on it every week. Setup first, then the method.
You bring a published adventure and prep it in Foundry. The AI runs it, from one scene to the whole DM's side, and does not invent the plot.
Start here
New to Familiar? These four, in this order, take you from an empty module to a first session.
Not playing D&D 5e? See what Familiar does on your system.
Get started
Install Familiar and connect an AI. The rest of the guides build on these two.
Connect Claude, ChatGPT, or Gemini
What to have ready, three ways through the setup, the check that proves the link, and the faults every client shares.
Pick your assistant
One page per assistant that has its own way in. Open the one you already pay for.
Claude in Foundry: Desktop or Code
Anthropic builds both clients, so no agent app sits in the path. How you add each one, and what differs between them.
ChatGPT in Foundry via Codex
Codex is the route in, as a tab in the ChatGPT app or as Codex CLI, on every plan including Free.
Gemini in Foundry via Antigravity
Antigravity or a Gemini API key in Familiar's own chat window: which suits your table, and the snags only Antigravity has.
Grok in Foundry via Grok Build
xAI's terminal agent is the one Grok that speaks to a Foundry game. One command registers Familiar and a second proves the link.
Muse Code in Foundry: one settings file
Where Muse Code keeps Familiar and your model, what /mcp has to say before the first ask, and the fixes for its installer.
Choices around the connection
MCP or a provider key, which model to run, and whether to run one yourself.
MCP vs API: which to choose
MCP rides a subscription you already hold. A provider key buys a specific model and tighter spend. The numbers, and what only the built-in chat can do.
Choosing an AI model
Which model holds a tool chain together, where to get one, and when to turn the thinking up or down.
Running a local LLM
Run the model on your own PC, so your world never leaves the machine. One settings tab and one switch. Without a discrete GPU, expect minutes per turn.
Run your game
For a GM with Familiar connected and a session coming up.
How to play D&D with AI
Where a bare chat window breaks down, and the method that starts where it stops: who runs what, and what a session looks like.
Prepping a published adventure for AI
Which parts of a published adventure go into journals, which onto sheets, and how to bake your rulings into the pages the AI reads.
Keeping your prep in Obsidian
Your vault is never copied into Foundry: the AI reads it where it is. The setup, and how to fence off the folders it should not see.
Writing characters the AI can play
Five lines make Garric the innkeeper, and a busier NPC gets a fuller anchor card. What he says when a player asks past the page.
Staying consistent across sessions
A long campaign overflows any context window. Keep a searchable record in Foundry so the AI reads from your notes, not a fading window.
Running combat with AI
Watch a troll's illegal claw get refused, verbatim, and see which calls the rules engine hands back to you.
Ways to play
For a small table, and for anyone building one like mine.
Playing solo and duet with AI
You take the player seat for once and Familiar runs the rest of the table. How a session goes, and the limits to know going in.
The setup I run at my own table
One PC, one player, a microphone, and an AI playing two heroes and every monster. The exact rig, and the order to build it in.
The rules I give my AI DM
A copy-paste rules pack for any AI running a game: roll only when it matters, run the adventure you prepared, never decide for the players.
Something stopped working? The faults every client shares, and the fix for each.
Need a map for tonight? The battlemap generator has its own page.
Giving the table a voice? Voices, music, sound effects and transcription have their own page.
Looking for the full tool list? See everything Familiar can do.