Hi Yuan,
it seems as Mistral is always expecting parameters for functions. The ones that cause the problem don't require any input, because they use the current user's context to find the relevant data.
I cannot give you the solution to solve the problem, but you can try debugging a little more by trying to find out how to send tools with empty input parameters to Mistral. For OpenAI, it is not a problem to have 0 inputs. If you know what to do, you might be able to manipulate the request before sending.
Alternatively (not the perfect solution, but helpful to move on) add a dummy input parameter of type string which you don't use. For this, just edit the three function microflows and add a parameter. This at least makes the request compatible with Mistral.
I was not finding much information about this problem other than this reddit forum post where someone complained as well ("Even that only seems to work correctly with passing a single function definition with some parameters. Passing multiple functions or even passing a function definition without parameters seems to break the model.")
Good luck and best regards
Liam