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Summer Engine in Cursor

Cursor is the most popular IDE for AI-assisted development. With Summer Engine’s MCP integration, you can build games without leaving Cursor: the AI adds nodes to your scenes, sets properties, imports assets, runs the game, and debugs errors, all through the same chat you use for code. This guide walks you through two setup options: a one-click install link (when supported) and manual configuration, which always works.

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Option 1: One-Click Install

Cursor supports MCP install deeplinks. Click the link below to add Summer Engine to your MCP servers:

Add Summer Engine to Cursor

Click to install Summer Engine MCP (opens Cursor)
If the link doesn’t work: Cursor’s deeplink format may change. Use Option 2 (manual config). It takes about 30 seconds and is reliable.

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Option 2: Manual Configuration

Manual setup gives you full control and works in all Cursor versions.

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Step 1: Create or Edit MCP Config

Cursor reads MCP servers from one of these locations:
  • Project-level: .cursor/mcp.json in your project root (recommended, stays with the project)
  • User-level: ~/.cursor/mcp.json (global, applies to all projects)
Create the file if it doesn’t exist. If it does, add the summer-engine entry to the existing mcpServers object.

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Step 2: Add the Summer Engine Config

{
  "mcpServers": {
    "summer-engine": {
      "command": "npx",
      "args": ["summer-engine", "mcp"]
    }
  }
}

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Step 3: Restart Cursor

Close and reopen Cursor so it loads the new MCP config. The MCP server starts when Cursor starts; it doesn’t connect to the engine until you first use a Summer Engine tool.

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Step 4: Verify

  1. Open Cursor Settings (Cmd+, or Ctrl+,)
  2. Go to MCP (or search for “MCP”)
  3. You should see summer-engine listed with 23 tools
If you don’t see it, check that the JSON is valid (no trailing commas, proper quotes) and that the file path is correct.

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Using Summer Engine in Cursor

Once configured, the AI has access to Summer Engine’s tools. You don’t need to mention “Summer Engine” in every message. If the AI knows you’re building a game and the tools are available, it will use them when appropriate. Example prompts:
  • “Add a Camera3D and DirectionalLight3D to the scene”
  • “Get the current scene tree so I can see the structure”
  • “Import this model: https://example.com/tree.glb and add it under the World node”
  • “Run the game and take a screenshot of what the player sees”
  • “Set the main scene to res://main.tscn”
Engine must be running. Summer Engine needs to be open with your project loaded. If you haven’t started it yet, run npx summer-engine run from your project directory, or open the project from the Summer Engine app.

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Troubleshooting

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”Summer Engine is not running”

The MCP server can’t connect to the engine. Fix:
  1. Open Summer Engine and load your project
  2. Or run npx summer-engine run from the project folder
  3. Wait a few seconds for the engine to start, then try your request again

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MCP server not appearing

  • Check the config path: .cursor/mcp.json must be in the project root (the folder you opened in Cursor)
  • Validate JSON: Use a JSON validator. A single missing comma or extra comma will break it
  • Restart Cursor: Fully quit and reopen, not just reload the window

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Tools return errors

If a specific tool fails, the error message usually explains why. Common causes:
  • Wrong node path: Paths use ./ prefix (e.g., ./World/Player). The root is ./ or ./Root depending on your scene.
  • Engine not ready: Some operations require the game to be stopped. Use summer_stop before making scene changes.
  • Invalid value format: Properties like position need engine string format: "Vector3(0, 10, 0)" not {x: 0, y: 10, z: 0}. See the Tools Reference for format details.

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Next Steps

Tools Reference

All 23 MCP tools with parameters and examples

Building a Game

Step-by-step: how an AI builds a full game with MCP

MCP Setup Overview

Prerequisites, architecture, 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.