The @cloudflare/workers-types package defines the type Service<MyEntrypointType>, which describes the type of a service binding. MyEntrypointType is the type of your server-side interface. Service<MyEntrypointType> applies all the necessary transformations to turn this into a client-side type, such as converting all methods to async, replacing functions and RpcTargets with (properly-typed) stubs, and so on. It is up to you to share the definition of MyEntrypointType between your server app and its clients. You might do this by defining the interface in a separate shared TypeScript file, or by extracting a .d.ts type declaration file from your server code using tsc --declaration.