How to Fix Unauthorized MCP Error in Antigravity (Step by Step) 2026

In this video, I’ll show you how to fix Error: calling "initialize": sending "initialize": Unauthorized - MCP error in Antigravity when trying to install or connect an MCP tool. This issue happens because the client needs to be manually authenticated. I’ll walk you through opening the MCP server manager, finding the tool with the red error line, running the authentication flow, approving access, pasting the authorization code, and refreshing the connection. After this quick fix, all tools will load correctly and Antigravity will work as expected. Tags antigravity, mcp, mcperror, unauthorized, errorfix, troubleshooting, devtools, webdev, backend, coding, programming, tutorial, stepbystep, workflow, developer, techguide, authentication, setup, configuration, codingtutorial