TypeScript decorator changing function signature

Question

I think this is probably a bit of a long shot, but here goes.

I'd like to create an artificial signature for a function that is being altered by a decorator.

@route('blar/blar')
someAction(route: string, params: Record<string, unknown>): Promise<void> {
  // Do stuff
}

someAction({ foo: 'bar' });

I have a decorator that injects a route variable into the first parameter of a function. You can then call the function, without the route parameter.

The backstory is that this is a project that is being converted from type-less JS to TypeScript. I'd prefer not to rework how the decorators work.

Can I spoof the signature of the decorated function, without fudging the types of the parameters? So that TypeScript ignores the route parameter in the signature? Sort of like an overload alias?