If you’re importing more than a few posts from an existing database then you should use a migration script.
There’s a skip_validations parameter you can pass in Ruby, but I don’t know if you can pass it with the API.
But also, do you really want to create a bunch of short posts that have very few different characters and are just like other posts? There are site settings for those that you can change if you search site settings for those words (entropy, minimum post length, min title similar length or allow duplicate titles)