"Envoy to New Worlds" is a 1963 science-fiction novel by Keith Laumer, published as one half of an Ace Double. The book is somewhere between a novel and a short story collection, as it tells six stories of one protagonist. The stories are in chronological order and lead into one another, so they could be considered either chapters, or stand-alone stories.
Jame Retief (almost always just "Retief") is a junior diplomat in the galactic consular service, working for the officious and incompetent Second Secretary Magnam. The galactic diplomatic service is almost uniformly bureaucratic and oblivious to what is going on around it. Retief has to take matters into his own hand, using his wits and fisticuffs. In each story, in around 20 pages, Retief has to really find out what is going on behind the facade, and through hook and crook defeat an alien invasion or gathering war. Since each story is only 20 pages long, the mystery and intrigue don't get too deep. After he solves the problem, he returns to work with his superiors none the wiser, and is disciplined for breaking some minor diplomatic protocol.
What I found interesting here is the combination of machismo and gentility of the protagonist. He is, as the stereotypes of sci-fi heroes of the time might go, a square-jawed loner who bucks the system and isn't afraid to knock heads to get what he wants---but he is also an idealist who can't stomach injustice and uses his skills to prevent wars and conflicts. This book fits in with something I previously noted, which was that Ace Doubles often did feature stereotypical white male heroes who could easily be taken as signs of post-war self-confidence. At the same time, the book criticizes militarism and entrenched power structures.
After reading this book, I learned two things that put it in context: Laumer was in reality, a member of the US Diplomatic Service while writing these books, and that this was the first in a series of novels and short stories featuring Retief that Laumer would continue to write for the next two decades.