What
An MCP server is an outside service that gives Claude extra tools. Some of them need you to sign in, and Claude Code keeps that sign-in alive by refreshing a token, a kind of temporary pass.
If the sign-in server refused the last token refresh for an MCP server, Claude Code no longer tries to sign in again from inside the conversation. It reports that it cannot do so and tells you to run /mcp reconnect or /mcp to fix the connection yourself.
Why
When sign-in to an MCP server fails this way, you now get a clear next step instead of a failed attempt.
Names in the bundle/mcp
/mcp
overview modified, high confidence
Within the beta, [MCP tunnels](https://platform.claude.com/docs/en/agents-and-tools/mcp-tunnels/overview) and [dreaming](https://platform.claude.com/docs/en/managed-agents/dreams) are in a more limited research preview. To enable them, [re…see the edit
/mcp
claude-tag modified, high confidence
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/mcp
How to Authenticate When Publishing to the Official MCP Registry modified, high confidence
| Request | `GET https://<domain>/.well-known/mcp-registry-auth`, sent with `Accept: text/plain` and `User-Agent: mcp-registry/1.0` |see the edit
/mcp
Quickstart: Publish an MCP Server to the MCP Registry modified, high confidence
"url": "https://github.com/my-username/mcp-weather-server",see the edit
/mcp
mcp-connector modified, high confidence
Session creation does not validate MCP connectivity or credentials. It does check each declared server’s host against the environment’s networking. With `limited` networking, session creation fails with a 400 error when a host is not allow…see the edit
/mcp
permission-policies modified, high confidence
Pass this `tools` (csharp, go: `Tools`) configuration when you create the agent. MCP toolsets support the same per-tool overrides, with `name` (csharp, go: `Name`) set to the tool name reported by the MCP server. See [Configure which MCP t…see the edit
/mcp
migration-guide modified, high confidence
Retrying the same request body doesn’t clear the error. To find these edits before you switch production traffic, run the test in [Test your code for prefix check failures](https://platform.claude.com/docs/en/build-with-claude/preserved-th…see the edit
/mcp
claude-tag modified, high confidence
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Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agrees
/mcp on overview
Anthropic's release notes agree
Fixed /mcp and /plugins opening an MCP server's page with the cursor on "Disable" when the server needs authentication but still holds its…