If you’re developing with Google’s Antigravity on a Mac, you might have  tried installing the Firebase MCP Server to give your AI over your database.

But if you use Homebrew to manage your tools, the default installation from the MCP "Store" on Antigravity likely failed. You might see errors like:

  • npm error code EACCES (Permission denied)
  • npm warn ERESOLVE (Peer dependency conflicts)
  • calling "initialize": EOF (Server disconnected)

This happens because the default configuration tries to use npx to fetch a temporary version of Firebase. This often conflicts with local permissions or fights with your system's Node.js setup.

Here is the 2-minute fix to get it running perfectly using your existing Homebrew installation.


The Solution

Instead of letting the editor try to download a new version of Firebase every time it starts, we will tell it to use the stable binary you already have locally.

Step 1: Find your Firebase path

Open your terminal and run:

# Bash
which firebase


If you installed via Homebrew on a Mac, the result is usually:

/opt/homebrew/bin/firebase

Copy this path. You'll need it in a second.

Step 2: Update the MCP Configuration

In the Antigravity Agent column, find the three dots on the top right corner.


Click the “MCP Servers”, then you will see the “Manage MCP Servers” showing on top right corner. 

Click on the Manage MCP Servers.

Look for the Firebase entry in the center column and click "View raw config".

Add the “firebase-mcp-server” into the “macpServers”:

# JSON
{
  "mcpServers": {
    …, // Other servers
    "firebase-mcp-server": {
      "command": "<path to your firebase cli installed by brew>",
      "args": ["mcp"]
    }
  }
}

Note: paste your specific path into the "command" field.


Why this is better

By pointing directly to the binary:

  • Zero Startup Lag: You don't wait for npx to resolve dependencies.
  • No Permission Errors: It runs with your user permissions, not root.
  • Stability: It uses the exact same version of CLI you use in your terminal.

Do Forget Authentication

The MCP server doesn't have a login screen. It reply on your system's credentials. If you aren't logged in, the AI will just say "I can't find any data."

Before you start prompting, open your terminal and run:

# Bash
# 1. Login to Google

firebase login
# 2. Select your active project
firebase use --add


Select the project you are currently working on. The MCP server uses this "active" project by default for all its queries.

What can you do now?

Now that the server is running, you don’t need to switch to the Firebase Console. Here are three practical ways to use this MCP server to speed up your development.

1. The One-Shot Staging Environment

Instead of clicking through the Firebase Console UI to set up a new environment for testing, just tell the AI to do it.

  • Prompt: "I need a new Firebase project called 'my-app-staging' for testing. Create it and tell me the new Project ID."
  • Tool Used: firebase_create_project

2. Instant Frontend Configuration

When you are setting up a new React or Vue app, you usually have to search for your API keys and App IDs. The AI can fetch them directly.

  • Prompt: "I am setting up a web app for my current project. Fetch the SDK configuration and format it as a .env file for me please."
  • Tool Used: firebase_get_sdk_config

3. Project List and Setup

If you work on multiple apps, it's easy to lose track of registered clients (iOS, Android, Web). You can ask the AI to audit your setup.

  • Prompt: "List all the apps registered in this project. Do we have an Android app set up yet? If not, create one with the package name 'com.example.myapp'."
  • Tools Used: firebase_list_apps, firebase_create_app

For more details on the Firebase MCP server's capabilities, please see the official web page.

Summary

Don't fight with npx permissions. If you are on a Mac, and manage your package with Homebrew. By using the absolute path to your binary, you get a faster, more stable AI partner that actually knows what's happening inside your Firebase project.