אני עייפה מכדי לקרוא חוזה ארוך בטלפון, ולכן אבדוק אותו בבית.

Because the speaker is feminine. In Hebrew, words like עייף / עייפה agree with the gender of the person speaking.

• אני עייפה = said by a woman
• אני עייף = said by a man

With אני, the verb usually does not show gender in the present tense, but adjectives and participles often do.

מכדי means something like too ... to ....

So עייפה מכדי לקרוא means too tired to read.

This is a fairly standard, slightly formal/written structure in Hebrew:

• adjective or state + מכדי
  • infinitive

Example:

• צעיר מכדי להבין = too young to understand

Yes. A very common alternative is:

אני עייפה מדי לקרוא חוזה ארוך בטלפון

That also means I’m too tired to read a long contract on the phone.

Very roughly:

• מדי is very common in everyday speech
• מכדי is correct and natural, but can sound a bit more formal or literary

Because Hebrew normally uses the infinitive after מכדי. The infinitive usually begins with ל־, so:

• לקרוא = to read

This is the same basic pattern as in English too tired to read, where to read is also an infinitive.

Because את is usually used before a definite direct object, not an indefinite one.

Here:

• חוזה ארוך = a long contract (indefinite)

So no את is needed.

Compare:

• קראתי חוזה ארוך = I read a long contract
• קראתי את החוזה הארוך = I read the long contract

In Hebrew, adjectives usually come after the noun.

So:

• חוזה ארוך = a long contract
• ספר מעניין = an interesting book

Also, the adjective must agree with the noun in gender and number:

• חוזה is masculine singular
• so ארוך is also masculine singular

In this sentence, בטלפון most naturally means on the phone, meaning on a phone screen or device.

So the idea is not reading aloud over a phone call, but reading it on a phone.

In modern everyday Hebrew, people might also say:

• בפלאפון
• בסמארטפון

But בטלפון is understandable and natural in context.

לכן means therefore, so, or for that reason.

The ו־ at the beginning means and, so literally ולכן is and therefore. In natural English, though, you would usually just translate it as so or therefore.

It sounds a bit more formal or polished than אז.

Compare:

• ולכן = more formal/written
• אז = more conversational

Because Hebrew future-tense verbs already include the subject information.

אבדוק by itself already means I will check.

So אני is optional here. You can add it for emphasis, contrast, or clarity, but you do not need it.

• אבדוק אותו בבית = neutral, natural
• אני אבדוק אותו בבית = more emphasis on I

The א־ marks first person singular future in Hebrew.

The root here is בדק meaning check/examine. In the future:

• אבדוק = I will check
• תבדוק = you will check / she will check
• יבדוק = he will check

So the first letter is part of the future-tense pattern, not part of the root itself.

אותו means it or him for a masculine singular object.

It refers back to חוזה, and חוזה is masculine, so the pronoun must also be masculine:

• חוזה → אותו

If the noun were feminine, you would use אותה instead.

Hebrew can sometimes leave out an object if it is obvious from context, but here אותו is very natural because it clearly refers back to the contract.

So:

• אבדוק אותו בבית = I’ll check it at home
• אבדוק בבית = possible in some contexts, but less clear here because it leaves unsaid what is being checked

Using אותו makes the sentence smoother and more explicit.

Because בבית means at home or in the house, while הביתה means homeward / to home.

Here the sentence is about the place where the checking will happen, so בבית is the right choice.

• אבדוק אותו בבית = I’ll check it at home
• אלך הביתה = I’ll go home

It is natural and correct, but it leans a little toward a more polished or written style because of מכדי and ולכן.

A more conversational version might be:

אני עייפה מדי לקרוא חוזה ארוך בפלאפון, אז אבדוק אותו בבית.

Both versions are good. The original just sounds a bit more formal.