I was a fan of The Dirty Pair since forever. I remember them when their series was still airing the first time. I remember their Movie, their original OVA, the later OVA, and the OVA series. I even remember their cameo in the Crusher Joe movie. And I always knew they were based on a series of light novels, which apparently I read the first one once a long time ago, but I did not remember it--so here I go again.
Yuri (obviously the better one--objectively) and Kei are Trouble Consultants for a ginormous organization called the 3WA/WWWA or World Work and Welfare Association. They are very good at their job, which is to solve problems. They are so good at it in fact that when they are done, there is no problem anymore--ever--seriously, the planet the problem was on is gone. But, it is never their fault--because the 3WA computer clears them of any wrongdoing. Which means they have a perfect record and get deployed more.
This is a story of their work.
Sadly it is told from Kei's viewpoint. Did I mention that Yuri is objectively best girl?
The story is not going to win any prizes. It is kind of outdated. Being told from Kei's viewpoint means it spends a lot of time describing the physical characteristics of what I assume are her idea of tasty men, and because she is the inferior of the two TCs, she spends a lot of time complaining about being second fiddle to Yuri--see also pining.
It is a great book for people like me, but YMMV. If you do like it, give the anime a try: Dirty Pair TV, then Affair of Nolandia, Then the OVA series, then the Movie, then the OVA.