AetherAether

Cursor MCP Setup

Configure Cursor IDE to connect to the Aether MCP server.

🤖Your Agent Has Access to All This

Once the Cursor MCP is connected, your agent will have full access to these docs. No need to learn this yourself...unless you want to!

Prerequisites

  • Cursor IDE installed
  • Node.js 18+ (for npx) or a downloaded bridge binary
  • Unity project with Aether SDK installed

Automatic Setup (Recommended)

Option A: One Command

Run this in your Unity project directory:

1npx aether-init

This downloads the bridge, installs the Unity SDK, and writes .cursor/mcp.json — all in one step.

Option B: Already Have the Bridge?

If you already downloaded the aether-bridge binary, run from your Unity project directory:

1./aether-bridge --setup-cursor

This writes .cursor/mcp.json pointing to the bridge binary. No manual editing needed.

✅Done!

After either option, reload Cursor (Ctrl+Shift+P → "Reload Window") and you're ready to go.

Manual Configuration

If you prefer to configure things by hand, create .cursor/mcp.json in your project root.

Windows

1{ 2 "mcpServers": { 3 "aether": { 4 "command": "C:/path/to/aether-bridge-windows-x64.exe", 5 "args": ["--stdio"] 6 } 7 } 8}

macOS

1{ 2 "mcpServers": { 3 "aether": { 4 "command": "/path/to/aether-bridge-darwin-arm64", 5 "args": ["--stdio"] 6 } 7 } 8}

For Intel Macs, use aether-bridge-darwin-x64 instead.

Linux

1{ 2 "mcpServers": { 3 "aether": { 4 "command": "/path/to/aether-bridge-linux-x64", 5 "args": ["--stdio"] 6 } 7 } 8}
ℹ️Path Format

Use forward slashes (/) in paths, even on Windows. Cursor handles the conversion automatically.

How It Works

When you configure MCP this way:

  1. Cursor launches the bridge automatically when it needs to use Aether tools
  2. Bridge starts in stdio mode - communicates via stdin/stdout instead of WebSocket
  3. Unity connects separately - run Unity in Play mode, it connects to the bridge on port 7890
  4. No manual terminal needed - Cursor manages the bridge lifecycle
✅Simpler Setup

This is easier than the old WebSocket approach - no need to manually start the bridge in a terminal!

Verification

After configuration:

  1. Reload Cursor (Ctrl+Shift+P → "Reload Window")
  2. Check the MCP status in Cursor's output panel
  3. Start Unity in Play mode
  4. In Cursor's AI chat, type: @aether snapshot

You should see a response with your game state!

Available Tools

Once connected, your AI can use all Aether tools (20 total). Core tools include:

| Tool | Description | |------|-------------| | aether_snapshot | Current Unity state + recent events + console | | aether_tail | Events + state changes over last N seconds | | aether_console | Query Unity stdout logs | | aether_last_run_answer | Answer engine for the last run | | aether_mark | Save a moment (clip) | | aether_clip | Create a time-window clip | | aether_package | Create a Capsule (Pro/Studio) | | aether_recon | Run 1 instrumentation plan | | aether_window | Run 2 probe timeline | | aether_proofclip_draft | Proof clip draft (Pro/Studio) | | aether_observe | Keyframes + deltas + logs | | aether_docs | Tool documentation |

See the Tools Reference for the full list and schemas.

Troubleshooting

Bridge Not Starting

Problem: Cursor shows "MCP server failed to start" or similar.

Solutions:

  1. Verify the path to the bridge binary is correct
  2. Make sure the binary is executable (chmod +x on macOS/Linux)
  3. Check Cursor's Output panel for error messages
  4. Try running the binary manually to see if it works: ./aether-bridge --stdio

Tools Not Appearing

Problem: Aether tools don't show up in Cursor.

Solutions:

  1. Reload Cursor completely (Ctrl+Shift+P → "Reload Window")
  2. Check .cursor/mcp.json syntax (valid JSON, no trailing commas)
  3. Verify the binary path uses forward slashes
  4. Check Cursor's MCP output panel for errors

Unity Not Connecting

Problem: Snapshot shows "Unity may not be connected".

Solutions:

  1. Make sure Unity is in Play mode
  2. Check Unity Console for "[Aether] Connected to bridge"
  3. Verify no firewall is blocking localhost:7890
  4. Ensure Aether.Init() is called in your game

Permission Denied (macOS)

Problem: macOS blocks the binary from running.

Solutions:

  1. Remove quarantine: xattr -d com.apple.quarantine ./aether-bridge-darwin-*
  2. Or right-click the binary → Open → Allow

For more help, see the Troubleshooting Guide.

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