MCP "needs you to sign in again" in Claude Code: reconnect without a new session

An MCP server or claude.ai connector that expires mid-session doesn't mean starting a new one. How to reconnect it in the terminal and in the cloud, tested with tokens that really expired.

Opening a new session because a connector expired throws the conversation away; reconnecting and staying in the same one keeps it

TL;DR In the terminal: /mcp, the server, Authenticate; if you already fixed it outside the session, /mcp reconnect all. In a cloud session: reconnect it at claude.ai/customize/connectors and ask Claude again in the same conversation.

MCP server "<name>" needs you to sign in again (run /mcp to re-authenticate) shows up when the login of an MCP server or a claude.ai connector expires. Nothing warns you when it expires: you see it the first time Claude tries to use it. What broke is the connection, not the conversation, so don't open a new session: reconnect and carry on.

What expires and what you see

An OAuth login keeps two tokens: a short-lived access token, and a refresh token used to get a new one. Tested on v2.1.319 against a local MCP server with real OAuth whose tokens were expired by hand:

What expires	What you see	What you do
Only the access token	Nothing: Claude Code gets a new one with the refresh token and retries the call	Nothing
Both	`MCP server "probe" needs you to sign in again (run /mcp to re-authenticate)`	Sign in again, in the same session

In the terminal

1. Sign in again from /mcp

/mcp, pick the server, Authenticate. The browser opens, you sign in, and the session confirms it:

❯ /mcp
  ⎿  Authentication successful. Connected to probe.

The next call works, conversation intact.

2. If you fixed it outside, reconnect

Here's the trap. If you sign in from another terminal with claude mcp login <name> after the open session has already failed, that session never finds out: it keeps returning MCP server "probe" needs authentication and doesn't even try again. /mcp shows it with two lines that disagree:

  Status:           ⚠ needs authentication
  Auth:             ✔ authenticated

The good token is already stored; what's missing is for the session to connect again. No browser needed:

❯ /mcp reconnect all
  ⎿  Reconnected 1 of 1 MCP server

If you sign in outside before the session fails, its next call picks up the new token on its own. That's why authenticating from the shell before you start avoids the interruption.

In a cloud session

The error is the same and also points you at /mcp, but in the cloud the connector is authorized by your claude.ai account, not by the session. You fix it at claude.ai/customize/connectors: connect it again, go through the service's login, and come back.

Tested with Google Slides in an open cloud session. Once it was disconnected, the first call failed with MCP server "Google_Slides" needs you to sign in again (run /mcp to re-authenticate). Once it was reconnected on claude.ai, the same session, with no restart and nothing else touched, read presentations again on the first try. In the cloud, a fix made outside does reach the open session.

When Claude checks your connectors, the desktop app shows you a card:

The connector card redrawn from a screenshot of the Spanish app: Google Slides with its Usar button and a link to explore 950+ more connectors

Don't use it to tell whether a connector works. With Google Slides disconnected it still offered the button that uses it (Usar in the Spanish app), while a connector you never connected gets Conectar. And that button connects nothing: it types a message into the chat for you (for Tella, "Use Tella for this") and leaves the connector as it was.

Reference

Where the session runs	Where connectors come from	Where you fix it	Does the open session pick it up?
Terminal, VS Code, JetBrains: your own MCP servers	Your config (`claude mcp add`, `.mcp.json`)	`/mcp`, Authenticate	Yes; fixed outside, only after `/mcp reconnect all`
Terminal, VS Code, JetBrains: claude.ai connectors	Claude Code fetches them from claude.ai	`claude.ai/customize/connectors`	Not tested
Cloud	The session's host passes them in	`claude.ai/customize/connectors`	Yes, no restart
Desktop, local or SSH	The desktop app passes them in	`claude.ai/customize/connectors`	Not tested

If the server never connects in the first place, the diagnosis is a different one: the "Failed to connect" decision tree.

Official docs: How connectors reach Claude Code · Authenticate with remote MCP servers

Requirements

/mcp reconnect all needs Claude Code v2.1.284 or later. Everything above was run on v2.1.319 on November 7, 2026.