MCP Mode & AI Agent Integration

Let AI agents manage your Minecraft instances through the Model Context Protocol — unique to Polymerium.

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What is MCP?

The Model Context Protocol (MCP) is a standard for AI agents to interact with external tools. Polymerium's CLI (trident) can run as an MCP server, exposing 30+ tools that AI agents can call directly.

This means you can ask an AI assistant to:

"Create a Fabric 1.21.4 instance with performance mods"
"Take a snapshot, then update Sodium to the latest version"
"Export this instance as a Modrinth modpack"

And it will do it — no manual clicks needed.

No other Minecraft launcher supports this.

Starting the MCP Server

trident --mcp

This starts an MCP server over stdio. Connect your AI client (Claude, Cursor, etc.) to it as a tool provider.

Configuration for AI Clients

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "polymerium": {
      "command": "trident",
      "args": ["--mcp"]
    }
  }
}

Cursor

Add as an MCP tool server in Cursor's settings, pointing to trident --mcp.

Other Clients

Any client that supports MCP over stdio can connect. The server speaks the standard MCP protocol.

Available Tools (30+)

Instance Tools

Tool	Description
`instance_list`	List all instances
`instance_inspect`	View instance details
`instance_create`	Create a new instance
`instance_delete`	Delete an instance
`instance_unlock`	Unlock an imported instance's source binding
`instance_reset`	Reset the build (clear build/ and live/)
`instance_export`	Export instance as a modpack
`instance_import`	Import a modpack file

Package Tools

Tool	Description
`package_list`	List installed mods
`package_search`	Search CurseForge / Modrinth
`package_add`	Add a mod by purl
`package_inspect`	View mod details
`package_enable` / `package_disable`	Toggle mods
`package_dependency_list`	List a mod's dependencies
`package_dependent_list`	List mods that depend on a given mod
`package_version_list`	List available versions
`package_version_set`	Pin a specific version

Loader Tools

Tool	Description
`loader_list`	List loaders for an instance
`loader_version_list`	List available loader versions
`loader_get` / `loader_set`	Get or set the loader

Config Tools

Tool	Description
`config_get` / `config_set`	Read/write configuration
`config_list` / `config_unset`	List or remove config keys

Account Tools

Tool	Description
`account_list`	List accounts
`account_add_offline`	Add an offline account
`account_remove`	Remove an account

Repository Tools

Tool	Description
`repository_list`	List configured repositories
`repository_status`	Check repository connectivity
`repository_add` / `repository_remove`	Add or remove repositories

Example Sessions

Creating a Performance Modpack

You: Create a Fabric 1.21.4 instance called "perf-pack" with Sodium, Lithium, and Iris.

Agent: I'll create the instance and add the mods.
  → instance_create("perf-pack", version="1.21.4", loader="fabric")
  → package_add("modrinth:sodium")
  → package_add("modrinth:lithium")
  → package_add("modrinth:iris")
  → instance_build("perf-pack")
  Done! Your "perf-pack" instance is ready to launch.

Safe Experimentation

You: Take a snapshot of my "skyblock" instance, then update all mods.

Agent:
  → instance_inspect("skyblock")   // confirm instance exists
  → snapshot_create("skyblock", name="before-bulk-update")
  → package_version_list(...)      // check each mod for updates
  → package_version_set(...)       // apply updates
  → instance_build("skyblock")
  Snapshot saved. All mods updated and redeployed.
  If anything breaks, restore the "before-bulk-update" snapshot.

Limitations

MCP runs over stdio — it's designed for local use, not remote servers.
Microsoft account login requires Device Code Flow, which isn't ideal for headless AI interaction. Use offline accounts for automated workflows.
The MCP server uses the same data directory as the GUI — don't run both simultaneously.

MCP Mode & AI Agent Integration

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