Breakdown of Mon cher ami m'a raconté une histoire inoubliable.
une
a / an (feminine)
l'ami
the friend (m)
avoir
to have
mon
my
Questions & Answers about Mon cher ami m'a raconté une histoire inoubliable.
Why is cher placed before the noun ami here?
Cher is one of those adjectives that changes meaning depending on its placement. When placed before the noun, it means "dear" or "beloved" (as in mon cher ami). If it were placed after the noun, it would mean "expensive" (like un repas cher for "an expensive meal").
Why does inoubliable go after the noun, while cher goes before?
In French, the standard rule is that adjectives go after the noun, especially longer ones like inoubliable (unforgettable) or those stating simple facts. Cher goes before the noun here because it belongs to a special group of adjectives that take on a figurative or emotional meaning when placed early.
Why isn't there an agreement on raconté if the person saying "me" (m') happens to be female?
Because m' is an indirect object in this sentence. The verb is raconter quelque chose à quelqu'un (to tell something to someone). In the passé composé, the past participle only agrees with a direct object that comes before the verb. Since the direct object here is une histoire and it comes after the verb, raconté doesn't change.
How do you know whether histoire means "story" or "history"?
It all comes down to context! The word histoire is used for both. Here, because a friend is "telling" (raconter) something, it clearly means "story". If the sentence were about a school subject or the past of a country, it would translate to "history".