firebase-auth-basics Skill for Claude: Add Firebase Sign-In to an App

firebase-auth-basics, from Google's Firebase team, guides your agent through enabling Firebase sign-in and wiring it into a web or mobile app.

Installs: 178.3K; on skills.sh
Stars: 497; on GitHub
Files: 5; besides SKILL.md
Updated: Oct 2026; last repo commit

firebase-auth-basics teaches the agent how Firebase Authentication works and how to set it up. It explains users, sign-in providers (email/password, Google and other federated providers, phone, anonymous, custom) and ID and refresh tokens, and recommends Google Sign In as the default.

For setup it adds an auth block to firebase.json for Google Sign In, anonymous and email/password, then runs deploy --only auth to make it live. Other providers are enabled in the Firebase Console. Client guides cover web, Flutter, Android (Kotlin) and iOS (Swift), and a rules guide shows request.auth checks.

It expects a Firebase project and a logged-in CLI, and points to firebase-basics for both.

Good for

Developers adding user sign-in to a web, Android, iOS or Flutter app
Teams that want Google Sign In, email/password or anonymous auth switched on from the CLI
Anyone writing Firestore or Storage rules that depend on request.auth

Install firebase-auth-basics

Claude Code

Copy this prompt.

Install the firebase-auth-basics skill in Claude Code. Run this command:

claude plugin marketplace add firebase/agent-skills
claude plugin install firebase@firebase

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js 20+, Google account.

The plugin route is the one the Firebase skills recommend for Claude Code. It installs all 13 skills in the repo and a Firebase MCP server, which .mcp.json starts with npx -y firebase-tools@15.32.1 mcp --dir . (version at review time). Restart Claude Code afterwards. The skills CLI route installs only the skills named. Every route needs Node.js 20 or newer, and the skills run the Firebase CLI through npx, so you also sign in to Firebase with a Google account. The README writes the marketplace as firebase/skills; the repository is firebase/agent-skills, the name the vendor Claude Code setup guide uses.

From the vendor's docs. Source.

What's in the skill

When it loads

Guide for setting up and using Firebase Authentication. Use this skill when the user's app requires user sign-in, user management, or secure data access using auth rules.

Sections in SKILL.md

Prerequisites
Core Concepts
Users
Identity Providers
Tokens
Workflow
1. Provisioning
2. Client Setup & Usage
3. Security Rules

Key facts

Author: firebase (GitHub: firebase)
Repo: firebase/agent-skills
License: Apache-2.0 (LICENSE and README); the Claude plugin.json says MIT
Installs on skills.sh: 178,287 as of 2026-11-02
GitHub stars (whole repo): 497 as of 2026-11-02
Last repo commit: 2026-10-30
Files: 6 files including SKILL.md (5 reference guides), no scripts
skills.sh audits: Gen Agent Trust Hub pass, Socket pass, Snyk warn
Made by: Google LLC (SKILL.md metadata); the Claude plugin calls itself the official Claude plugin for Firebase
Category: Identity

What it includes

Users, providers and tokens
A user has a uid, email, display name, photo URL and email-verified flag. ID tokens last 1 hour; refresh tokens get new ones.
Core concepts
auth block in firebase.json, then deploy --only auth
Only Google Sign In, anonymous and email/password can be enabled this way. The deploy step is required for the config to take effect. It warns not to put port numbers in authorizedRedirectUris.
Runs code · Provision via CLI
Other providers are enabled in the Firebase Console
The skill sends you to the console's Authentication providers page for any provider the CLI cannot enable.
Provision via Console
Web, Flutter, Android (Kotlin), iOS (Swift)
Four reference guides: client_sdk_web, flutter_setup, client_sdk_android and ios_setup.
Client setup guides
request.auth checks for Firestore and Storage
Examples: signed-in check, owner-by-UID check, field-based owner check, email_verified check. Firestore rules authoring goes to the firestore-rules-creation skill.
Security rules with auth

From the official docs

Permissions

Medium risk

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It deploys sign-in settings to your live project
The skill says you must run deploy --only auth after editing firebase.json. Check providers and authorizedRedirectUris first. github.com
It runs the latest Firebase CLI through npx
Commands use npx -y firebase-tools@latest, which downloads and runs the newest published package each time. You sign in to Firebase with your Google account. github.com
The plugin route adds a Firebase MCP server
The Firebase plugin ships an .mcp.json that starts `npx -y firebase-tools@15.32.1 mcp --dir .` with IS_FIREBASE_MCP=true, so a Firebase MCP server runs in your project folder. The pinned version was 15.32.1 at review time. The skills CLI route does not add it. github.com

Technical details

Talks to	Firebase and Google Cloud through the Firebase CLI
Scopes	Google account signed in to the Firebase CLI

Questions

What does firebase-auth-basics do?

It guides your agent through adding Firebase Authentication to an app: turning on providers, adding the client SDK and writing rules that use the signed-in user.

How do I install firebase-auth-basics in Claude Code?

Use the install box above. The plugin route installs every Firebase skill plus the MCP server. The skills CLI route installs this skill and firebase-basics, which its SKILL.md points to for project creation and login.

Which sign-in providers can it turn on?

Google Sign In, anonymous and email/password from the CLI. For other providers the SKILL.md sends you to the Firebase Console.

Why does Google Sign-In close immediately with an unauthorized-domain error?

The SKILL.md says the domain is not authorized. Add http://localhost to authorizedRedirectUris in firebase.json (no port number), or localhost to Authorized Domains in the Console.

Does it need an API key?

No API key is named in the SKILL.md. The Firebase CLI signs in with your Google account (npx -y firebase-tools@latest login), and most tasks need an active Firebase project.

Is firebase-auth-basics safe to use?

It can change your live sign-in settings: after editing firebase.json it runs deploy --only auth. Review the auth block before you let it deploy, especially redirect URIs and providers.

Information

updated Nov 2, 2026

Repository: firebase/agent-skills
Folder: skills/firebase-auth-basics

firebase/agent-skills skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 6

agent-skills README · github.com
firebase-basics Claude Code setup · github.com
Firebase plugin .mcp.json · github.com
firebase-basics Cursor setup · github.com
firebase-auth-basics SKILL.md · github.com
github.com · github.com