What
MCP servers are outside tools that Claude Code can connect to. Some come from connectors you set up on claude.ai, and those use a server type called claudeai-proxy. Claude Code now refuses that type anywhere you might write it yourself:
- Plugin validation reports an error for server types that only the host or claude.ai connectors use, and tells plugin authors to use type "http" instead. The plugin loader drops such a server when it loads.
- Adding a server by hand rejects
claudeai-proxy, with a message that says the type "is used only by claude.ai connectors" and points to claude.ai/customize/connectors. Before, only host-only types were rejected. - An MCP config file that declares a
claudeai-proxyserver has that server skipped. The message says to remove it from your MCP config and connect the service at claude.ai/customize/connectors, where it appears in Claude Code automatically, or to add it with type "http". Before, such an entry failed with a general config error. - An enterprise list of denied servers now also matches claude.ai connector entries, and extra admission checks apply.
Separately, after you switch accounts, claude.ai connector servers are no longer reconnected straight away. They are held aside until Claude Code has finished fetching your connectors again, then reconnected. If that fails, Claude Code logs "MCP re-dial of held claude.ai proxy entries after account switch failed".
Why
If you copied a claude.ai connector into a config file or plugin, you now get a clear explanation and a fix instead of a confusing error. Organisations that deny certain servers now also cover claude.ai connectors. After an account switch, connectors are reconnected only once your new account's list is ready.