What
MCP servers are outside programs that give Claude Code extra tools. Claude Code now leaves some of them out when it tells the model which servers failed or need you to sign in.
- The summary the model gets while waiting for MCP servers to start now filters entries out of its "failed" and "needs authentication" lists. When some were left out, an extra note says so. Before, every failed and needs-auth server was listed.
- MCP servers that belong to the host app itself are now hidden this way. If one fails, disconnects or needs sign-in, the model gets fixed instructions instead. It is told not to name the server, not to ask you to reconnect or sign in, and to say that something went wrong on the app's end.
- These app-owned servers are also left out of other hidden reminders to the model, including the one about deferred tool search, a way of loading tools only when they are needed, and the one about servers that need authentication.
- Sign-in-again, step-up and connection errors for these servers are replaced with the same fixed text.
Before, app-owned servers were treated like any other server, with advice to reconnect through /mcp.
Why
When the tool server built into the app you are using breaks, you are no longer asked to reconnect or sign in to something you cannot fix yourself. You are told the problem is on the app's side. Ordinary MCP servers you added still come with /mcp advice.
Names in the bundle/mcp
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on Edit docker-compose.yaml: increment the integer in the setup service's touched a line naming /mcp after this was published.
The **Needs certificate** badge next to the tunnel's name goes away once a certificate is registered. See [Add a CA certificate](https://platform.claude.com/docs/en/agents-and-tools/mcp-tunnels/console#add-a-ca-certificate).agents-and-tools/mcp-tunnels/deploy-compose see the edit
Confirmed since
Anthropic's documentation has since written up /mcp, on Error reference.
* For other reserved names to avoid, see [MCP configuration warnings](/docs/en/mcp#configuration-warnings)errors see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up /mcp, on Error reference.