Integration Guide
Google Antigravity + WHMCS
Connect Google Antigravity to WHMCS in under 10 minutes
Estimated time: 10 minutes · Transport: STDIO + SSE + HTTP
Quick Reference
- Min Version
- Antigravity 1.0+ (public preview)
- Transport
- STDIO + SSE + HTTP
- Public URL
- Not required
- Node.js
- Required
- AI Models
- Gemini 3, Claude, GPT-4o
- Concurrent Tools
- Unlimited (agent-managed)
- Avg Response Time
- 3-8 seconds per tool call, agents chain calls autonomously
Prerequisites
- WHMCS 8.0 or higher with admin access
- MCP Server addon installed and activated (installation guide)
- Google Antigravity installed (download here)
- Node.js installed (for npx, which bridges STDIO to SSE)
Step 1: Generate an API Key
- Go to your WHMCS admin panel
- Navigate to Addons > MCP Server
- Click Generate New API Key
- Copy the API key and save it securely. You will need it in the next step.
Important: The API key is shown only once. If you lose it, you will need to generate a new one.
Step 2: Open Google Antigravity MCP Configuration
Navigate to the MCP configuration file inside Google Antigravity:
- Open Google Antigravity and start (or open) an Agent Session
- Click the “...” menu at the top of the side panel
- Select MCP Servers
- Click Manage, then View raw config
This opens the mcp_config.json file where you will add your WHMCS MCP Server.
Step 3: Add the WHMCS MCP Server Config
Add the following configuration to your mcp_config.json (replace the URL and API key with your own):
// Antigravity: mcp_config.json
// Access via: Agent Session > "..." > MCP Servers > Manage > View raw config
{
"mcpServers": {
"whmcs": {
"command": "npx",
"args": [
"mcp-remote",
"https://your-whmcs.com/modules/addons/mx_mcp/mcp.php",
"--header",
"Authorization:Bearer YOUR_BEARER_TOKEN"
]
}
}
}
// Troubleshooting: if the server does not connect, replace "npx" with the absolute path.
// Antigravity runs in an isolated environment and may not inherit your shell PATH.
// macOS/Linux: run "which npx" in your terminal to find the path (e.g. /usr/local/bin/npx)
// Windows: run "where npx" in Command Prompt (e.g. C:\Program Files\nodejs\npx.cmd)
// Docs: https://antigravity.google/docs/mcpTip: Save the file after adding the configuration. Google Antigravity auto-reloads MCP configuration, so no restart is needed.
Step 4: Test the Connection
- Open any Agent Session in Google Antigravity
- Type:
Get WHMCS system status - If the connection is working, you should see system information from your WHMCS installation
Success! If you see WHMCS system info, the connection is working. Try more queries like “List all active clients” or “Show overdue invoices”.
Troubleshooting
“MCP server not found”
- If MCP Server does not appear, restart Google Antigravity
- Ensure the JSON in mcp_config.json is valid (no trailing commas, proper quotes)
- Make sure Node.js is installed and npx is available in your PATH
- The MCP Store also lists available servers, but custom servers need manual config via the raw config file
“Connection refused” or timeout
- Ensure your WHMCS URL is accessible from your machine
- Check that the MCP Server addon is activated in WHMCS
- Ensure your API key is valid and has not been revoked
- Check if your WHMCS has HTTPS enabled (required for remote connections)
“Permission denied”
- Verify API key permissions match your needs (read-only vs full-access)
- Go to Addons > MCP Server in WHMCS and check API key permissions
- Check MCP Server logs in WHMCS admin > Addons > MCP Server > Logs
- Ensure the API key has access to the tools you are trying to use
Upgrading from v1.1.x?
If you set up the MCP Server before v1.3.0, the authentication method changed. Here is what is different and how to update your config.
Previous method (v1.1.x)
Still works. In v1.3.0, authentication changed from API Keys to Bearer tokens, and the endpoint changed from sse.php to mcp.php. If you are still on v1.1.x, this is how it was configured:
{
"mcpServers": {
"whmcs": {
"command": "npx",
"args": ["-y", "@anthropic/mcp-remote",
"https://your-whmcs.com/modules/addons/mx_mcp/mcp/sse.php"],
"env": { "MCP_API_KEY": "your-api-key-here" }
}
}
}To upgrade: update the config to use mcp-remote (not @anthropic/mcp-remote), change sse.php to mcp.php, and replace the MCP_API_KEY env var with a --header Authorization:Bearer YOUR_TOKEN arg.