Struggeling with 422 Error returns from mistral.ai

I am currently using mistral.ai and got it working just fine. Now I want to use more sophisticated functions like agents and tools. Whenever I try using those function, I get an error 422 in return with no further explanation.

  1. I call agents directly with the a API Call (Screenshots provided)
  2. I call functions via the advanced options (Screenshots provided)

Since both calls get me the 422 error, I feel I lack some basic understanding but cannot figure out what I am missing.

Any help would be highly appreciated.