Claude Can't See Your Gmail or Sheets? Connect Apps with /mcp

Have you asked Claude Code "find the client email in my Gmail" only to get "can't access your mail"? AI by default can't see your external apps (mail, sheets, GitHub, etc.). The pathway that connects this is MCP, and /mcp is the command that manages those connections. The moment you connect, Claude Code starts doing your real work.

Definition

/mcp is a command to manage external app connections (MCP) during a conversation.

Here, "MCP (Model Context Protocol)" is a standard connection pathway linking Claude Code with external services. Just as a USB cable connects a computer and a device, MCP connects AI with apps like Gmail, Google Sheets, and GitHub. With /mcp you can see which apps are connected, attach new ones, and do login (OAuth) authentication.

(For reference, "OAuth" is a standard login method where you grant permission by just clicking an "allow access to this app" button, without handing over your password directly. If you want to manage it from the terminal, there's also the claude mcp command.)

How to use it (by difficulty)

Basics — view connection status

Type into the chat box.

/mcp

This shows the list of currently connected servers (apps) and each one's connection status on screen. You can see at a glance what's connected and what's in a state needing authentication.

Applied — authenticate an app login

/mcp

Pick an app needing authentication on the /mcp screen and the login (OAuth) procedure begins. Usually the browser opens with an "allow access to this app?" screen. Click allow and authentication finishes, and from then on Claude Code can handle that app's (e.g., Gmail's) data.

Advanced — manage connections per task

connect only the apps you need, and disconnect when done

Attach and detach tools to fit the task. Connect only Gmail for mail-organizing work, only GitHub for code work, and so on. Cleaning up unused connections narrows the permission scope, making it safer.

Common pitfall — connected but not authenticated

If you added an app to the list but still get "no access permission," it's often a case where you connected but didn't finish login (OAuth) authentication. Adding a connection and authenticating are separate steps. Check on the /mcp screen whether that app's status shows "authentication needed," and finish the login procedure.

A real case

Before entrusting it with organizing piled-up mail, I first authenticated the Gmail connection with /mcp. After clicking allow-access once in the browser, Claude Code could read and sort the mail. After the work was done, I cleaned up the connection and withdrew the permission. Opening the pathway only when needed, and closing it when done.

Use it like this too

• Add connection & authenticate: Attach a new app and approve the OAuth login.
• Terminal version: In the terminal, you can also manage it with the claude mcp command.
• Chain apps: Connect Gmail and Google Sheets together and a single flow like "read mail and organize it into a sheet" becomes possible.
• Per-task connection: Attach only when needed, and clean up when done to minimize permissions.

Tip: You don't need to keep all apps connected always. Connecting only the apps your current task needs, as you go, is cleaner for both security and management.

How others use it

• Thanks to HTTP transport, you can simply connect GitHub MCP with one command line (no Docker needed). — Adding an MCP server to Claude Code (MCPcat)
• Handle issue/PR management, CI failure analysis, and release management from the terminal with the official GitHub MCP. — GitHub official MCP Server

Wrap-up

The key is one sentence. The more you connect, the stronger Claude Code gets. MCP is the cable linking AI and your apps, and you manage those connections with /mcp. Just remember that adding a connection and login authentication are separate steps. As you attach the tools you need one by one, Claude Code gradually starts doing your real work for you.

Based on: Claude Code v2.1.154 (2026.05)