Antigravity Setup

Antigravity has both surfaces covered, and they work differently:

Surface	Method	Recall
Antigravity CLI	Plugin — pre-prompt hook	Automatic, every turn
Antigravity IDE	MCP server	Model calls the tools

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Antigravity CLI

Same tier as Claude Code: a pre-prompt hook injects an <nc-context> block before each turn, so recall happens whether or not the model thinks to ask.

Install

npm install -g @nexus-catalyst/antigravity-plugin
export NC_PLUGIN_API_KEY="your-plugin-key"
nc-antigravity install
nc-antigravity status

Your Plugin API key comes from Account → API Keys. Put the export in your shell profile so it survives new sessions.

Commands

nc-antigravity install      # Register the NC hooks
nc-antigravity uninstall    # Remove them, leaving other hooks intact
nc-antigravity status       # Check installation state and API key

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Antigravity IDE

Step 1: Open the raw config

In the agent side panel: … → MCP Servers → Manage MCP Servers → View raw config.

That opens ~/.gemini/config/mcp_config.json (global), or .agents/mcp_config.json if you want the server scoped to one workspace.

Step 2: Add the server

~/.gemini/config/mcp_config.json

{
  "mcpServers": {
    "nexus-catalyst": {
      "serverUrl": "https://mcp.nexus-catalyst.com"
    }
  }
}

Caution

Antigravity does not accept url or httpUrl for remote servers. If you copy the snippet from our Cursor guide, which uses url, the server will simply not appear — with no error to tell you why.

Step 3: Sign in

Nexus-Catalyst supports dynamic client registration, so Antigravity handles OAuth itself — there is no client ID, client secret, or bearer header to add.

If it does not prompt, open Agent Settings → Customizations and press Authenticate next to nexus-catalyst. Tokens are stored at ~/.gemini/antigravity/mcp_oauth_tokens.json and refresh on their own.

Step 4: Add the instruction set

The IDE has no pre-prompt hook, so add the Agent instruction set to your agent rules. Without it the tools are present but unused.

Note

Menus move. If what you see does not match the steps above, MCP in Antigravity IDE is the authority — it is maintained by Google and updates when their UI does.

Troubleshooting

The server does not appear in the IDE

Nine times out of ten this is the serverUrl key — see the caution above. url and httpUrl fail silently.

Authentication never prompts

Use the manual path: Agent Settings → Customizations → Authenticate.

CLI hooks are not firing

Run nc-antigravity status and confirm both hooks are listed and NC_PLUGIN_API_KEY is set.

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Need help? Common Issues · support@nexus-catalyst.com