How to fix PHPStan error if I want to use an array as callback function for a tool?

[robiningelbrecht]

I have this code in place. Tis should be a valid callback right?

PHPstan then throws this error which makes sense):

any idea how this can be fixed?

[ilvalerione]

->setCallable(fn() => call_user_func([$this, 'getUserWorkout']))