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Summer Engine in VS Code & GitHub Copilot

VS Code and GitHub Copilot’s coding agent support MCP (Model Context Protocol). With Summer Engine’s integration, the AI can control your game engine: add nodes to scenes, set properties, import assets, run the game, and debug, all from within your coding workflow. This guide covers both VS Code (with Copilot or other AI extensions) and GitHub Copilot’s agent mode—they use the same MCP configuration.

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Prerequisites

  • VS Code: With GitHub Copilot (agent mode) or another MCP-aware AI extension
  • Node.js: For running the MCP server (Node 18+)
  • Summer Engine: Installed and running with your project open

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Configuration

VS Code reads MCP servers from:
  • Project-level: .vscode/mcp.json in your project root (recommended, stays with the project)
  • User-level: Run MCP: Open User Configuration from the Command Palette (⇧⌘P)

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Step 1: Create or Edit the Config File

Create .vscode/mcp.json in your project root, or open the user config via MCP: Open User Configuration. If the file already exists, add Summer Engine to the existing servers object.

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Step 2: Add Summer Engine

{
  "servers": {
    "summer-engine": {
      "type": "stdio",
      "command": "npx",
      "args": ["summer-engine", "mcp"]
    }
  }
}
Alternative: Use MCP: Add Server from the Command Palette for a guided setup. Choose “Standard I/O” and enter npx as the command with summer-engine mcp as arguments.

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Step 3: Restart VS Code

Close and reopen VS Code (or reload the window) so it loads the new MCP config. The Summer Engine MCP server starts when VS Code starts; it connects to the engine on the first tool call.

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Step 4: Verify

  1. Run MCP: List Servers from the Command Palette
  2. You should see summer-engine with 23 tools
  3. Try a prompt in Copilot Chat: “Use Summer Engine to add a MeshInstance3D with a BoxMesh to the scene”
If the node appears in Summer Engine, the setup is working.

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Using Summer Engine with VS Code / Copilot

Once configured, the AI can use Summer Engine’s tools when you ask for game-related changes. Example prompts:
  • “Add a Camera3D and DirectionalLight3D to the scene root”
  • “Get the scene tree from Summer Engine”
  • “Import this model and add it to the World node: [URL]”
  • “Run the game and capture a screenshot”
  • “Set the project’s main scene to res://main.tscn”
Engine must be running. VS Code and Copilot talk to Summer Engine over localhost. Open your project in the engine first, or run npx summer-engine run from the project directory.

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Troubleshooting

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”Summer Engine is not running”

Start Summer Engine and open your project. The MCP server connects to the engine’s local API on port 6550. The engine writes a token to ~/.summer/api-token when it starts.

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MCP server not appearing

  • Config path: Verify .vscode/mcp.json is in your project root (the folder you opened in VS Code)
  • JSON validity: Ensure no trailing commas, proper quotes, and valid JSON structure
  • Restart: Fully quit and reopen VS Code

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Tools return errors

See the Tools Reference for parameter formats. Common issues: wrong node path format (./World/Player), invalid property values (use engine string format like "Vector3(0, 10, 0)"), or the game running when scene edits are attempted (stop it first with summer_stop).

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Next Steps

Tools Reference

All 23 MCP tools with parameters and examples

Building a Game

How an AI builds a full game using MCP

MCP Setup Overview

Architecture, prerequisites, and other IDEs

CLI Reference

summer install, run, create, and more
Need help or have questions? Reach out to our founders at founders@summerengine.com or join our community on Discord for fast responses.