This paper explores the complexity of implementing directory protocols by examining their mechanisms - primitive operations on directories, caches, and network interfaces. We compare the following protocols: Dir1B, Dir4B, Dir4NB, DirnNB, Dir1SW and an improved version of Dir1SW (Dir1SW⁺). The comparison shows that the mechanisms and mechanism sequencing of Dir1SW and Dir1SW⁺ are simpler than those for other protocols. We also compare protocol performance by running eight benchmarks on 32 processor systems. Simulations show that Dir1SW⁺'s performance is comparable to more complex directory protocols. The significant disparity in hardware complexity and the small difference in performance argue that Dir1SW⁺ may be a more effective use of resources. The small performance difference is attributable to two factors: the low degree of sharing in the benchmarks and Check-In/Check-Out (CICO) directives.