Supercheck

Symptom	Cause and fix
`404 not_found` from `/api/mcp`	MCP is off on this server. A self-hosting admin must set `MCP_SERVER_ENABLED=true` and recreate the app
The browser never opens	Run the tool's auth command (for example `/mcp` in Claude Code) and choose supercheck. Check the URL ends in `/api/mcp`
`401` after working earlier	The token expired and could not refresh. Sign in again from the client, or reconnect
`403 access_denied`	Access was removed. If the app was disconnected, reconnect and approve again. If you were removed from the organization or your account is banned, ask an admin; access returns once it is restored, with no reconnect needed
`429 rate_limited` or `too_many_concurrent_requests`	One app may send up to 300 requests a minute and 4 at a time; all your apps together 600 a minute and 8 at a time. Wait for the `Retry-After` seconds, or send fewer calls at once
`503 rate_limiter_unavailable`	The server's rate limiter is temporarily unavailable, so the call was refused rather than let through unchecked. Retry after the `Retry-After` seconds. An administrator should check that Redis is reachable
`400 batch_too_large`	A single request may carry at most 20 calls. Split larger batches
Project missing on the approval screen	You can only share projects you can access. Ask an owner to add you
`forbidden` from a tool	Your role cannot view that resource type. Ask for a role that can
The server crashes on start with a `BETTER_AUTH_URL` error	`BETTER_AUTH_URL` must be the public HTTPS URL (`http://localhost:3000` is accepted for local use). The Docker setup derives it from `APP_DOMAIN`
Calls fail behind a proxy	Make sure the proxy passes the `Authorization` header through to `/api/mcp`
Stdio-only client	Bridge with `npx mcp-remote https://your-supercheck-host/api/mcp`

To inspect the server directly, run npx @modelcontextprotocol/inspector and connect to https://your-supercheck-host/api/mcp with the Streamable HTTP transport.

Troubleshooting