different-ai/openwork · error · Error

Failed to inspect MCP tools (${response.status}).

Error message

Failed to inspect MCP tools (${response.status}).

What it means

Thrown by useMcpConnectionTools when GET /v1/mcp-connections/:id/tools returns a non-ok status (30000ms timeout). getRequestError reports the server's error message or 'Failed to inspect MCP tools (<status>)'. The inspection then cannot produce a tool catalog or a parsed ExternalMcpToolPolicy.

Source

Thrown at ee/apps/den-web/app/(den)/dashboard/_components/mcp-connections-data.tsx:307

    disabledTools: value.disabledTools,
    updatedBy: value.updatedBy,
    updatedAt: value.updatedAt,
  };
}

export function useMcpConnectionTools(connectionId: string, enabled: boolean) {
  const { orgId } = useOrgDashboard();
  return useQuery({
    enabled: enabled && Boolean(orgId),
    queryKey: mcpConnectionQueryKeys.tools(orgId, connectionId),
    queryFn: async (): Promise<ExternalMcpToolCatalog> => {
      const { response, payload } = await requestJson(
        `/v1/mcp-connections/${encodeURIComponent(connectionId)}/tools`,
        { headers: getOrgScopeHeaders(requireOrgId(orgId)) },
        30000,
      );
      if (!response.ok) {
        throw getRequestError(payload, response, `Failed to inspect MCP tools (${response.status}).`);
      }
      if (!isRecord(payload) || !Array.isArray(payload.tools)) {
        throw new Error("MCP tool catalog response was incomplete.");
      }
      const policy = parseExternalMcpToolPolicy(payload.policy);
      if (!policy || !payload.tools.every(isExternalMcpTool)) {
        throw new Error("MCP tool catalog response was incomplete.");
      }
      return { tools: payload.tools, policy };
    },
  });
}

export function useUpdateMcpConnectionToolPolicy(connectionId: string) {
  const queryClient = useQueryClient();
  const { orgId } = useOrgDashboard();
  return useMutation({
    mutationFn: async (input: Pick<ExternalMcpToolPolicyView, "allDisabled" | "disabledTools">): Promise<ExternalMcpToolPolicyView> => {

View on GitHub (pinned to 2b7df46e8a)

Solutions

1. For 401/403, re-authenticate and ensure a valid org id is passed (requireOrgId throws earlier if absent).
2. For 404, refresh the connections list; the connection was deleted or the id is stale.
3. For 502/504/timeout, verify the remote MCP server is reachable/healthy and retry; consider raising the timeout.
4. For 5xx, retry with backoff and inspect Den server logs.
5. Handle isReauthRequiredError to start the re-auth flow.

Example fix

// before
const { data } = useMcpConnectionTools(orgId, connectionId);
// after
const { data, error } = useMcpConnectionTools(orgId, connectionId);
if (error) {
  if (isReauthRequiredError(error)) startReauth();
  else if (/\((404)\)/.test(error.message)) refetchConnections();
  else showError(error.message);
}

// before fetching tools
if (!orgId) throw new Error("Select an organization first");
if (!connections.some(c => c.id === connectionId)) throw new Error("Unknown MCP connection");

function isTransientToolError(err: unknown): boolean {
  return err instanceof Error && /\((502|503|504|408)\)/.test(err.message);
}

useQuery({
  queryKey: mcpConnectionQueryKeys.tools(orgId, connectionId),
  queryFn: () => fetchTools(),
  retry: (count, err) => count < 2 && isTransientToolError(err),
});

When it happens

Trigger: Non-ok response when fetching the tool catalog for a connection: 401/403 when org scope headers (requireOrgId(orgId)) are missing or the user lacks access to the connection, 404 when the connection id is wrong or removed, 408/504 when the remote MCP server is slow to enumerate tools (30s timeout exceeded server-side), 502 when the upstream MCP server is unreachable from Den, 5xx server faults.

Common situations: Inspecting a connection whose remote MCP server is offline or slow; deleted/stale connection row in the UI; missing org selection so scope headers are invalid; remote server auth (OAuth) expired so Den cannot list its tools.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

• Failed to configure plugin connection (${response.status}).
• Failed to update MCP tool policy (${response.status}).
• Failed to load MCP connectors (${response.status}).
• Failed to load MCP presets (${response.status}).
• Failed to look up the MCP server (${response.status}).

AI-assisted analysis of different-ai/openwork@2b7df46e8a (2026-09-01). Data as JSON: /api/errors/e6d614fed3959c06. Report an issue: GitHub.