I'm not totally clear what you mean by "apart from job-specific skills". Remember: Everything MBB firms are looking for during the interview are job-specific skills. That is what is both challenging and super great about consulting, and in my experience working for McKinsey! You are testing on exactly the skills that will make you successful on the job and which you will continuously develop throughout your career. This is not a theoretical interview (unlike many other jobs). The interview is very true to what you will do on the job.
So... what are they looking for? Many things, including:
- Strong problem-solving skills: Can you take a problem, understand what the client needs (define), break down the problem into relevant solvable parts (structure), tackle the most impactful parts first (prioritise), figure out what analysis is needed to tackle that part (workplan), do the quantitative and qualitative analyses (analysis), understand what the findings mean to the question (synthesise), and provide a sound recommendation to the client (recommendation) - this is what consultants do day-in and day-out!
- Effective communication: Can you effectively communicate to anyone and everyone - both to understand what's going on and to get people bought into your solution
- Confident Leadership: Can you lead the problem solving and lead people to an effective solution. Do you have the focus, strategy, persistence, experience, etc.
- Personable Teamwork: Can you work with other people and do so in a way where you are still showing leadership but also leveraging other people's strengths
- Additional Interpersonal Skill: Do you come across as credible, confident, ambitius, excited (about solving problems and working with people), persistent, nice (!), personable, analytical, emotionally intelligent, etc. Basically, will people enjoy working with you? :)
... and many more. Those are just a few things.
Finally, Remember: Every firm is different in what they emphasise. So I'd recommend really getting to know the firms intimately - go to their events, meet with ex-consultants, and study their websites.
The best thing I did when I was trying to learn these skills was to work with ex-consultants directly. So feel free to book sessions with me and we can get working on these skills in a practical way :)
All the best with your journey into consulting :)!