The Catechism in Questions & Answers

432. How else are the Apostles described?

The Apostles are also described as

“Ambassadors for Christ”—The statement: “Now then, we are ambassadors for Christ, as though God were pleading through us: we implore you on Christ’s behalf [...]” (2 Corinthians 5: 20) expresses that Jesus Christ works through the Apostles in His church.
“Stewards of the mysteries of God”: a “steward” (1 Corinthians 4: 1) is responsible for the “house”, namely the congregation. Here the Apostles see to it that the proclamation of the word occurs in a manner corresponding to the gospel and that the sacraments are dispensed in the mind of Jesus Christ. The Apostles ordain ministers and establish order in the congregation.