The article isn’t a very technical one. I’d wager when they say tooling they mean any in house program they use as a tool, as opposed to what we as programmers would think of, like compilers, dev tools etc.
Ocaml has a pretty robust ecosystem of good dev tools and build tools.
If you're talking about me (GP), I meant that Jane Street has built an entire ecosystem around OCaml, from their customer-facing and backend software to traditional OCaml tooling (like build systems). That being said, all I know is from the podcast I linked. I haven't touched OCaml (yet?) myself.
The VS Code plugin is, like, 90% of the developer experience of most devs. The fact that it's rock-solid in OCaml should automatically bump us up to at least a B grade. Meanwhile the dune build system is powerful and flexible, and compile times are actually blazing fast, unlike Rust's famous slow builds. So yeah, there are pros and cons on each side, I wouldn't say it's a clear win.
Ocaml has a pretty robust ecosystem of good dev tools and build tools.