ReScript Rest is very flexible, and if you miss something, let me know about it in issues, and I’ll add it. For example, if your server uses Hono.js it’s not difficult to add an integration for it, so both client and server side are 100% typesafe.
As for the need to manually describe the contract, we are discussing with @zth the solution to codegen ReScript Rest from OpenAPI, but this will probably happen after ReScript v12 is released 