As a user of OCaml I have to disagree. Rust requires far too many type annotations and they are mostly unnecessary and clutter everything up (particularly with it's very heavy syntax). In OCaml my editor shows me types if I mouse over a variable, and if I need to document the code I can do that, but I don't need to.
Without that, you lose out massively on readability and error message quality.
In Sail, I have IDE type inlays working but it barely helps with reachability because half the types are inferred as generic.