I'll keep this short and sweet.
Their primary role is enhancing a clients career.
Let's see if you have the right manager around you and what a manager actually is.
A Manager is a:
According to Billboard books, "Managers are people or firms that work with record companies, producers, agents, promoters, publicists and anyone else that's necessary. The objective of a manager is simple: To make sure everyone pulls together with effectiveness and enthusiasm to make the artist shine. If that sounds like a strict order, just know that the reality of doing it consistently is even more challenging.
Manager Do's and Don'ts
What a manager does, better yet, what they don't do.
Promoting and exploiting – That's a Music Publisher (See above of the things a manager is to focus on for you to be a success)
Book your shows – That's a Booking Agent (Booking your shows and getting you paid gigs is not their job. They can partner and network with resources to get you access to these things, but that's really the job of a booking agent... which you (the artist) pay for.
Pay your bills (Cell phone, studio time, showcases, etc.) - Don't even get me started. Investing in yourself is up to you. If a manager invests their own money into your career, they have become investors, not managers. Be careful with toting this line, as you may end up with less ownership of your works even after a possible split up from your management team.
Keeping this short, simple, and to the point will help you define who's already around you and if you had in mind the right things a manager is to be doing during your evaluation.