How to fix: MCP server not connecting / tools not showing up
Cause
The server config, transport, or auth is misconfigured, so the client can’t reach or authenticate to the MCP server.
The fix
- 1Verify the server config in your client (command/URL, transport type) matches what the server expects.
- 2Check authentication — many hosted MCP servers need OAuth, not a plain API key; the two are different auth systems.
- 3Confirm the server is actually running and reachable from the client’s environment (network/firewall).
- 4Restart the client after config changes so it re-discovers the server’s tools.
- 5Read the server logs — most connection failures are auth or transport mismatches that the logs name directly.
Prevent it
Use a well-built MCP server with clear auth, health checks, and logging so connection issues are obvious and rare.
Frequently asked questions
What causes “MCP server not connecting / tools not showing up”?
The server config, transport, or auth is misconfigured, so the client can’t reach or authenticate to the MCP server.
How do I prevent “MCP server not connecting / tools not showing up” from recurring?
Use a well-built MCP server with clear auth, health checks, and logging so connection issues are obvious and rare.