@Iguanadelmar @HeavenlyPossum @PallasRiot Yes, that's basically how I see it. Not saying that everybody calling themselves a Marxist were wrong, of course. But in the 20th century, "Marxism" was mostly – with significant exceptions – an attempt to understand capitalism in order to implement it effectively through the state, not very related to any actual project for overcoming capitalism.
As the so-colled council communists understood quite well, and in line with later theoretical currents like Wertkritik.
I think Marx had the intention to write no less than 6 bands of Capital, one of them dedicated to the state, but never written. Whatever he insisted, I think contemporary Marxian thinkers like Michael Heinrich or Søren Mau are pretty good at theorizing the relation between state and capital at a general level. Not that the state is necessarily just a "tool", but that it is inseparable from capital. Most obviously because it depends on money, which it can only get by taxing the surplus of capital, meaning that the creation of a surplus (within a wage-system) becomes a top priority of the state.