Is credit score of 718 with $1000 credit limit considered good to buy a house in the U.S?

Your credit score is fine.

Your credit limit doesn't matter because that limit just applies to the card (or cards) and has NOTHING to do with getting a mortgage - except that any revolving credit accounts you have might lower the amount you could be approved for when applying for a mortgage. So, if you have a card with a $1,000 limit, then your total available mortgage limit could be $1000 less because of that revolving credit. After all, if you use that credit line, it is a debt you would owe and it would affect your ability to pay the mortgage.

Now, what about your time on your job. At least six months is required and at least two years is preferred.

What about a down payment. At least 3% is usually required and the more you have, the better it would be.

You need to look at the costs of homes in the area you would like to live. You need to save up the down payment. You need to have enough time on the same job.

When you think you have the basics covered, then do a little more research on being a first time home buyer.

After you have done all that, then you can check with your bank about finding out the mortgage limit you could be approved for based on your income and down payment. Then you will know what homes you can look at. After all, why look at a home that you could never get approved for - so BEFORE you actually start looking - know your price range.

718 is fine. Do you have 6+ months at a full time job with good income and a down payment of at least 3% and ideally more?

718 is good enough for the score.

Mortgages don't have "credit limits" because they aren't revolving debts. You will be qualified for a one-time loan for the amount needed to purchase your house. That qualification process will look at your financial situation in depth, including things like your income, length of time at your current job, other debt, etc.

Sounds like you have a lot to learn before you buy a house. I suggest you look for a first time home buyer class in your area or search for articles and videos about the subject.

The credit limit is too low. You'd need to borrow about $100,000 or more for your mortgage, plus have a 20% or more down-payment.

The other factors are income, and money available for a down payment. This might or might not be considered good, due to many other factors.