Gmail Headless OAuth2

Set up Gmail API OAuth2 on servers without a browser. The standard gmail-mcp-multiauth setup command calls open() to launch a browser and listens on localhost:3000 — this fails on headless CLI servers. This skill provides the manual workaround.

When to Use

• Setting up Gmail API access on a headless server (no GUI browser)
• gmail-mcp-multiauth setup fails or hangs waiting for browser callback
• Need to re-authorize after token expiry
• Adding new Gmail accounts to an existing setup

Prerequisites

• GCP project with Gmail API enabled
• OAuth 2.0 Desktop App credentials (client_secret JSON downloaded)
• Each Gmail account added as "test user" in GCP OAuth consent screen (unless app is verified/published)

Pitfall: GCP Test Users (CRITICAL)