How to declare types for Cypress tasks with minimal duplication?

Question

I define a function

function a(arg: X): Y { ... }

...
on('task', { a })

for use as a Cypress task, and can add types:

declare global {
  namespace Cypress {
    interface Chainable {
      task(event: 'a', arg: Parameters<typeof a>[0]): Chainable<ReturnType<typeof a>>;
    }
  }
}

Repeat for each task (omitting arg where necessary). Is there a way to decrease repetition? Of course, I could write ... arg: X): Chainable<Y>, but then they could go out of sync with a's definition and the compiler wouldn't catch it.