What's the role of 好了 in 你叫我(name)好了?
In Chinese, the particle 好了 is used to mean "OK".

So in the sentence


  你叫我马丁好了。


this would be translated as "You can call me Martin, OK."



好了 is also used to suggest something where you are not expecting a response:


  现在我带你去看他好了。 = I'll take you to see him now.


In this case, the person could still refuse or suggest now is not the right time. But by using the 好了, the speaker is suggesting that the other party is likely to go ahead with the suggestion.

Contrast this with a sentence where 好吧 is used, which is more offering a suggestion:


  我们现在去看他好吧？ = Let's go and see him now, OK? or How about we go and see him now?




Also note that 好了 can be used in another context to indicate completion, e.g.:


  你吃好了没有? = Have you finished eating?