How to use Roblox MCP with Antigravity CLI.

Antigravity CLI shares the .gemini root with Gemini CLI and Antigravity / Antigravity IDE, but it uses a separate MCP config file.

Prerequisites

Antigravity CLI installed
Node.js (v18.0.0 or higher, with npx available)
Roblox Studio plugin installation complete

Registering the MCP Server

Global Config File

Add/merge the following into the global MCP config file for Antigravity CLI.

OS	Path
macOS / Linux	`~/.gemini/antigravity-cli/mcp_config.json`
Windows	`%USERPROFILE%\.gemini\antigravity-cli\mcp_config.json`

{
  "mcpServers": {
    "weppy-roblox-mcp": {
      "command": "npx",
      "args": ["-y", "@weppy/roblox-mcp@latest"]
    }
  }
}

Workspace Config

If you only want the MCP server in one project, you can put the same JSON in .agents/mcp_config.json at the project root.

The public one-line installer and web install page target the global path (~/.gemini/antigravity-cli/mcp_config.json) because it applies across the user account.

Connection Test

Launch Roblox Studio → Plugins tab → WEPPY → Connect

Enter the following in Antigravity CLI:

Tell me what is currently selected in Roblox Studio

Use /mcp in the CLI to check MCP server status

Troubleshooting

Server Won’t Start

Run the MCP server directly to see the error:

npx -y @weppy/roblox-mcp@latest

Connection Fails

Confirm the Roblox Studio plugin shows Connected status
Check that port 3002 is not blocked by a firewall
Use /mcp in Antigravity CLI to check server status
Make sure you did not edit Gemini CLI’s ~/.gemini/settings.json or the Antigravity IDE config by mistake

Antigravity CLI Setup