Aonghus is right. Intonation and the shifting of the stress would normally tell you which is referring to what.
quote:1. He has broken the hammer.
2. He has the broken hammer.
3. He has the breaking-hammer (hammer used for breaking things).
I can't speak for Connachta and Ulster but in Munster, one would probably say as follows:
Tá an casúr briste aige /tɑːn kɑˈsuːr ˌb'r'iʃd'ɪ ɡ'e/ = He has broken the hammer
Tá an casúr briste aige /tɑːn ˌkɑsuːr ˈb'r'iʃd'ɪ ɡ'e/ = He has the broken hammer/breaking-hammer
However, I note that Ó Sé (62) says that such phrases where the primary stress is shifted across to a following stressed syllable of a following adjective or a noun in the genitive are confined to a certain number of set expressions. Ó Cuív (241) merely say that there is a tendency to do so but doesn't say that such practice is confined to certain set expressions.
Another way of telling them apart is that one would be more likely to bring the prepositional pronoun to the front when saying that "he has the broken hammer/breaking hammer"; "Aige sin atá an casúr briste". You would also say "casúr chun briste" for a "breaking hammer".