Unable to overwrite default browsers for a job with API

Hello everyone, I’m trying to run a job with an API call and it works fine, but if I add executionParameters body with the browsers I want the job to run on, I get “412 Precondition Failed”. What am I doing wrong?
This is what I’m adding to the body:
“browsers”: [

Hi @mihalis .

Did you add the agent ID ?

The execution parameters body should look like this for example:

Oh, I see, thank you. I thought the default agent would be used if not specified. But how can I set all the browsers to headless in the parameters? From what I see, I can only set Chrome and Firefox as headless, with parameters “ChromeHeadless” and “FirefoxHeadless”.