Connector connected but unusable: the documented causes

The connector says "connected" but the plugin cannot actually reach your tool. The documented causes (October 2026 docs), in check order:

1. The service is not reachable from Anthropic's cloud

In Cowork, connectors run through Anthropic's cloud, so the service must be reachable from the public internet. A tool on your laptop, behind a VPN, or on a private network can show as configured and still be unreachable at run time. This is the first thing to rule out for self-hosted tools.

2. The per-connector sign-in never completed

Each connector asks for its own sign-in and access approval the first time a plugin uses it. A half-finished OAuth flow - approved in one browser tab, abandoned in another - leaves a connector that looks added but has no usable authorization. Disconnect and redo the sign-in deliberately.

3. You are on the wrong surface for that connector

A local MCP server runs only when the session runs on your computer - the desktop case. A Cowork session in Anthropic's cloud cannot use it. Remote MCP-based connectors travel; local ones do not. The component rules are in which features carry over.

4. An admin restricted it

On Team and Enterprise plans, admins can restrict plugins and disable local MCP servers. A connector that works for a colleague but not for you on the same plan is usually a policy difference, not a broken setup - ask the admin.

5. What the connector may do was never granted

Connectors have their own access scopes: what a plugin can read or write through one is spelled out in plugin permissions. If the plugin can read but not write, or sees some data but not all, the granted scope is the ceiling.

Sources

• Use plugins in Claude - Claude Help Center
• Plugins overview - Claude Docs