What
An MCP server is an add-on that gives Claude extra tools. Organizations can set strictPluginOnlyCustomization in managed settings, the settings an administrator controls. When it is true, or is a list that includes mcp, claude mcp add now refuses to add a server. The message says your organization allows only MCP servers that plugins provide, and suggests installing a plugin that provides the server or asking your administrator.
Why
Under that policy you now get a clear refusal when you add the server. Before, the server was added and then never loaded.
Names in the bundlestrictPluginOnlyCustomizationclaude mcp add
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 Control MCP server access for your organization touched a line naming strictPluginOnlyCustomization after this was published.
| [`strictPluginOnlyCustomization`](/docs/en/settings-reference#strictpluginonlycustomization) is `true` or includes `mcp`, and the user runs `claude mcp add` | [`Cannot add MCP server: your organization's managed settings allow only MCP s…managed-mcp see the edit
Confirmed since
Anthropic's documentation has since written up strictPluginOnlyCustomization, on Error reference.
You ran `claude mcp add` or `claude mcp add-json` while your organization's managed settings set [`strictPluginOnlyCustomization`](/docs/en/settings-reference#strictpluginonlycustomization) to `true` or to a list that includes `mcp`. With …errors see the edit
Added since
A small documentation edit on Connect Claude Code to tools via MCP touched a line naming claude mcp add after this was published.
* **Reserved names**: Claude Code reserves the names of its built-in servers, including `workspace`, `claude-in-chrome`, `computer-use`, `Claude Preview`, and `Claude Browser`. If your configuration defines a server with a reserved name, C…mcp see the edit
Confirmed since
Anthropic's documentation has since written up claude mcp add, on Configuration reference.
When set, Cowork, Chat and Code sessions do not connect a plugin's remote server whose URL matches an entry. The key works with or without `allowedPluginMcpServers`; a server that matches both lists stays blocked. In a Code session that re…third-party/claude-desktop/configuration see the edit
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up claude mcp add, on Configuration reference.
Anthropic's release notes agree
Fixed claude mcp add reporting success when managed settings restrict MCP servers to plugins; it now refuses and says what to do, instead of…