Use your Studio models from Claude, ChatGPT and Codex

Every app uses the same address:

https://api.myrlin.io/mcp

Apps you use in a browser or on a phone sign in to Forge with your account. Coding tools such as Claude Code and Codex use an AI key, which you make in the Link to your AI panel on your assets page. Name the server myrlin-forge when you add it, so it does not clash with other servers.

1. Open Add Myrlin Forge to Claude, or go to Customize, then Connectors, then Add custom connector.
2. Name it Myrlin Forge and use the address above.
3. Click Connect, sign in to Forge, choose what Claude can use, and approve.

One connector covers claude.ai, Claude Desktop and the Claude mobile apps. Claude’s free plan allows one custom connector. On Team and Enterprise plans, an Owner has to add the connector for the organization first; members then connect it themselves.

1. In ChatGPT, open Plugins, choose the plus button, then Add custom MCP server, and create it as a plugin.
2. Name it Myrlin Forge, use the address above and choose OAuth.
3. Connect, sign in to Forge and approve.

Make an AI key in the Link to your AI panel, then run:

claude mcp add --transport http myrlin-forge https://api.myrlin.io/mcp --header "Authorization: Bearer <YOUR_FORGE_AI_KEY>" -s user

Or sign in without a key: add the server without the header, run /mcp in Claude Code, choose myrlin-forge and sign in to Forge.

claude mcp add --transport http myrlin-forge https://api.myrlin.io/mcp -s user

Keep the key in an environment variable, not in a file.

setx MYRLIN_FORGE_API_KEY <YOUR_FORGE_AI_KEY>

$env:MYRLIN_FORGE_API_KEY = "<YOUR_FORGE_AI_KEY>"

export MYRLIN_FORGE_API_KEY=<YOUR_FORGE_AI_KEY>

Then add the server:

codex mcp add myrlin-forge --url https://api.myrlin.io/mcp --bearer-token-env-var MYRLIN_FORGE_API_KEY

Or add it to ~/.codex/config.toml. A longer tool timeout helps while a build is followed:

[mcp_servers.myrlin-forge]
url = "https://api.myrlin.io/mcp"
bearer_token_env_var = "MYRLIN_FORGE_API_KEY"
tool_timeout_sec = 120

To sign in instead of using a key, add the server without the variable and run codex mcp login myrlin-forge.

[sandbox_workspace_write]
network_access = true

Cursor, VS Code and other apps that take an HTTP MCP server: use the address above and send the header Authorization: Bearer <YOUR_FORGE_AI_KEY>. The server accepts an AI key or an OAuth sign-in, and nothing in a query string.

In a coding tool such as Claude Code or Codex, which can write files into your project:

• “Add my Forge model Frost Hydra to my Hytale server mod with its walk and attack animations.”
• “Add a frost breath effect to the Frost Hydra, then download the new Hytale pack into ./Server/mods.”
• “Give me the Minecraft package for my Frost Hydra that works without mods, and tell me where to put it.”
• “Wire the Frost Hydra into my Hytale plugin: copy the pack, register the model, and hook its attack clip to the attack state.”
• “Generate a blocky iron golem for Hytale with walk and attack animations. Quote it before building.”

In a chat app such as claude.ai or ChatGPT, which gives you links but cannot write into a folder on your computer:

• “List my Forge models that have animations and tell me which would fit a desert dungeon.”
• “Generate a blocky iron golem for Hytale with walk and attack animations. Quote it before building.”
• “Give me the Hytale pack download link for my Frost Hydra and tell me where to put it.”
• “Make the Ember Fox’s tail twice as long. Show me the price first, then give me the new version’s files for Blockbench.”

Name a model the way it appears in your library, or paste its asset id from its page.

The server also offers the four guides (hytale, minecraft, blockbench, prompting) as resources at forge://guides/<topic>, and a few ready-made prompts in Claude Code and claude.ai.

The AI can give you a ready package for each game and, in a coding tool, put it in your project. What each package holds, where its files go, how to merge it into a Hytale or Minecraft project you already have, and how to rename the mod id are on the integration page.

Every build is quoted first. The AI has to tell you the price and use the exact quoted number when it starts the build, and AI apps ask for your approval before a tool that spends runs, unless you told them to always allow it. Builds use your normal Forge credits; buying credits stays on the pricing page.

You can set a spending limit when you make a key or approve an app: credits per day, credits per build, or both. Leave it empty for no limit. You can also turn building off and keep the connection read-only. Change any of these later under Settings in the Link to your AI panel.

Free accounts can start 3 builds a day through AI. Keep building in Studio on forge.myrlin.io with your credits, or subscribe for unlimited AI builds. The count covers all your keys and connections and resets at midnight UTC.

An AI key works only with Myrlin Forge MCP. It is shown once when you make it; Forge stores only a hash. Making a new key replaces the old one.

Your key and your linked apps are listed under Link to your AI in your account Settings, and in the Link to your AI panel on your assets page (the library header, or any model). Revoke the key or remove an app there; it stops working at once. Settings there change what each one can see, whether it can build, and its spending limits.

The AI sees only your own account, and only the models you chose if you limited it. It cannot delete models, change your subscription or buy credits.

• The app says it is not signed in. Remove the connector or server and add it again, or make a new AI key.
• Codex gets a 401 right after `setx`. The terminal you ran setx in does not have the variable yet. Open a new terminal, or use the PowerShell form above.
• A download fails in Codex. The default sandbox has no network. Approve network access or set network_access = true, as shown in the Codex section.
• “Free accounts can start 3 builds a day through AI”. Wait for the reset time the message gives (midnight UTC), keep building in Studio on forge.myrlin.io with your credits, or subscribe for unlimited AI builds.
• A download link stopped working. Links last 15 minutes. Ask the AI for the package again.
• The model is missing. If you limited the connection to some models, the others are hidden from it. Change it under Settings in Link to your AI (account Settings, or any model on your assets page).

This documentation is also available as plain markdown at https://forge.myrlin.io/docs/mcp.md. The server itself answers get_guide with the same file placement steps for hytale, minecraft, blockbench and prompting.