AGMS2

AGMS2 is a GameMaker Studio 2 tooling monorepo built around three pieces:

• a local MCP server that can inspect and modify .yyp, .yy, and .gml files
• a VS Code-compatible extension for editing a GMS2 project entirely from the editor
• a GML builtins/skills data package used for documentation, prompts, and editor features

The goal is to make a GameMaker project feel like a first-class codebase inside modern editors such as VS Code, Cursor, and VSCodium.

Packages

• packages/mcp-server
  Local MCP server for GameMaker projects. It exposes project metadata, asset reads/writes, build/run commands, search, and room/object mutation tools.

• packages/vsc-extension
  VS Code/Cursor extension with a GMS2 explorer, GML language tooling, MCP lifecycle management, and read-only webviews.

• packages/gml-skills
  Prompt-ready GameMaker guidance plus built-in functions, variables, and constants used by the extension’s grammar, completion, hover, and signature help.

Current Features

MCP server

• Opens a .yyp project and indexes project assets
• Reads scripts, object events, rooms, macros, extensions, and project metadata
• Creates and edits scripts, objects, rooms, sprites, and object events
• Sets object sprite and parent
• Renames and deletes assets
• Searches and replaces across .gml
• Adds and removes room instances
• Runs build/run/clean commands through the GameMaker CLI
• Watches the project and refreshes internal metadata on file changes
• Emits MCP resource-change notifications so editor clients can refresh automatically
• Exposes a normalized asset index for editor integrations

VS Code extension

• Custom gms2Explorer tree view that mirrors the GMS2 IDE
• Opens scripts and object event files directly from the explorer
• Context actions for:
  • create object
  • create script
  • add event
  • set sprite
  • set parent
  • delete asset
• Commands for:
  • open project
  • refresh explorer
  • build project
  • run project
  • create object
  • create script
  • search GML
  • add event
• GML language support:
  • TextMate syntax highlighting
  • language configuration
  • built-in completions
  • asset-name completions
  • hover docs
  • signature help
  • go to definition
  • lightweight diagnostics
• Read-only webviews:
  • room preview
  • object inspector
• Automatic MCP process management with status bar connection state

GML data/skills

• Built-in function signatures and descriptions
• Built-in constants and variables
• Prompt-oriented GameMaker best-practice references for common systems

Repo Layout

AGMS2/
├─ packages/
│  ├─ gml-skills/
│  ├─ mcp-server/
│  └─ vsc-extension/
├─ package.json
├─ pnpm-workspace.yaml
└─ tsconfig.base.json

Requirements

• Node.js 20+
• pnpm
• GameMaker Studio 2 installed if you want to run actual builds

Install

From the repo root:

pnpm install

This is important now that the extension package has its own dependencies.

Running the MCP Server

Build it:

pnpm --filter @agms2/mcp-server build

Run it against a project:

node packages/mcp-server/dist/index.js --project "/absolute/path/to/MyGame.yyp"

Optional SSE mode:

node packages/mcp-server/dist/index.js --project "/absolute/path/to/MyGame.yyp" --sse --port 3001

You can also configure the GameMaker binary by creating gms2-mcp.config.json in the project root:

{
  "gmsBinaryPath": "C:/Program Files/GameMaker/GameMaker.exe",
  "buildTarget": "Windows",
  "runtimePath": null,
  "watchMode": true,
  "logLevel": "info"
}

The extension also passes gms2.gmsBinaryPath and gms2.buildTarget through environment variables when it starts the server.

Running the Extension

Fastest way in VS Code / Cursor

1. Run install once:

pnpm install

2. Build the MCP server:

pnpm --filter @agms2/mcp-server build

3. Build the extension:

cd packages/vsc-extension
node ./scripts/generate-gml-assets.mjs
node ./scripts/build.mjs

4. Open the repo in VS Code or Cursor.

5. Start an Extension Development Host:

   • open the Run and Debug panel
   • choose Run GMS2 Extension
   • press F5

6. In the Extension Development Host window:

   • run GMS2: Open Project
   • pick a .yyp
   • wait for the status bar to show GMS2: Connected

Installed VSIX setup

If you install the extension as a normal .vsix, also set:

• gms2.serverPath

Point it at your built MCP server file:

/absolute/path/to/AGMS2/packages/mcp-server/dist/index.js

The installed extension needs this because the MCP server currently lives in the AGMS2 repo, not inside the packaged VSIX.

Manual command-line build

If you only want to rebuild the extension bundle:

cd packages/vsc-extension
node ./scripts/build.mjs

Watch mode:

cd packages/vsc-extension
node ./scripts/build.mjs --watch

Publishing

Extension

The extension is designed for Open VSX first:

pnpm --filter agms2-vsc-extension package
pnpm --filter agms2-vsc-extension publish:ovsx

GitHub Releases are also automated for the VSIX. Bump the extension version in packages/vsc-extension/package.json or run one of:

pnpm release:patch
pnpm release:minor
pnpm release:major

Then push main. The workflow will build agms2-vsc-extension-<version>.vsix and publish a GitHub release tagged v<version>.

Marketplace

The manifest is structured so a VS Code Marketplace publish path can also be added if desired.

Important Notes

• The extension expects the MCP server build output at packages/mcp-server/dist/index.js.
• For a normally installed VSIX, set gms2.serverPath explicitly.
• Build and run commands only work when the GameMaker executable path is configured.
• The current diagnostics are intentionally lightweight. They are warnings, not a full semantic compiler.
• The webviews are read-only on purpose in this version.

Documentation

• MCP server details: packages/mcp-server/README.md
• Extension details: packages/vsc-extension/README.md
• GML data/skills: packages/gml-skills/README.md