Learn Hardcore Japanese: tomodati ni renraku wo site, saihu wo motte kite moraimasu. - I contact a friend and have them bring my wallet.

Here 友達に means “to (my) friend,” and 連絡をして is the te-form of the verbal noun 連絡をする (“to contact/notify”). Together it means “contact my friend” or “get in touch with my friend.”

Why is the particle に used after 友達 instead of を?

When you use 連絡をする, the person you contact is marked with に (an indirect object or target marker). The を attaches to the noun 連絡 because 連絡 is a verbal noun and を marks the direct object of する there.

What function does the て in 連絡をして、財布を持ってきて serve?

The て-form here links two actions in sequence: “contact my friend, and (then) have them bring my wallet.” It’s a common way to join verbs to show that one action follows another.

How does 持ってきてもらいます work? What is the nuance?

This is 持ってくる (“to bring”) in the te-form plus もらう (“to receive a favor”). Literally it means “receive the favor of someone bringing (something to me).” In English we’d say “have someone bring (something for me).” It emphasizes that I’m the beneficiary of the action.

Why use もらいます instead of くれます?

Both express receiving a favor, but from the speaker’s perspective. ～てくれる focuses on the doer doing something for me: “My friend does me the favor of bringing it.” ～てもらう focuses on me receiving that favor (and often implies I requested it). In polite or formal contexts, ～てもらいます is common when explaining what you’ll have someone do.

Who is the implied subject of this sentence?

Japanese often omits the subject when it’s clear from context. Here the speaker (私 or “I”) is the implied subject: “I will contact my friend and have them bring my wallet.”

Could I say this more casually? What about more politely?

Casual:
友達に連絡して財布持ってきてもらう。
Polite (more formal):
友達に連絡して、財布を持ってきていただきます。
Here いただきます is the humble form of もらう, raising politeness.