Concise description of primary organic reaction types mechanisms
The book you are looking for is The Art of Writing Reasonable Organic Reaction Mechanisms by Robert Grossman.

One of the book's publishers offers this description of the book:


  Intended for students of intermediate organic chemistry, this text shows how to write a reasonable mechanism for an organic chemical transformation. The discussion is organized by types of mechanisms and the conditions under which the reaction is executed, rather than by the overall reaction as is the case in most textbooks. The treatment emphasizes unifying principles, showing how common mechanisms link seemingly disparate reactions.
  Each chapter discusses common mechanistic pathways and suggests practical tips for drawing them. Worked problems are included in the discussion of each mechanism, and “common error alerts” are scattered throughout the text to warn readers about pitfalls and misconceptions that bedevil students. Each chapter is capped by a large problem set.
  The author has drawn on his own research and the current literature to ensure that appropriate attention is given to topics across the range of modern organic chemistry. The text is unique in its inclusion of a chapter on reactions mediated or catalyzed by transition metals, an area in which mechanistic understanding is now essential. Relatively new topics such as olefin metathesis and cycloaromatization are covered without giving short shrift to more traditional areas such as carbonyl chemistry. The text assumes a basic knowledge of organic chemistry. It can be used either in a formal course or by students working on their own, and will be particularly useful for graduate students studying for qualifying examinations. It will also be useful to students and researchers in biochemistry, pharmacology, and inorganic chemistry.


Each of the book's chapters are $50 \pm 30$ pages and are packed full of example problems.  Each chapter is organized according to the class of mechanism, not around particular reactants or products.  The chapters are:


The basics.
Polar reactions under basic conditions
Polar reactions under acidic conditions
Pericyclic reactions
Free-radical reactions
Transition-metal-catalyzed and -mediated reactions
Mixed mechanism problems


The author maintains a good web site with additional problems, additional worked examples, and answers to every problem in the book.  You can get a sense of the content of the book by browsing Amazon or by looking some of the answer .pdf files, available for free from Springer.

I found this book very helpful in improving my mechanistic understanding of various types of reactions.