In 1 Corinthians 1:1, is Paul a “called-apostle” or “called to be an apostle”?

(1 Corinthians 1:1) Παῦλος κλητὸς ἀπόστολος Χριστοῦ Ἰησοῦ διὰ θελήματος θεοῦ καὶ Σωσθένης ὁ ἀδελφὸς (KJV) Paul, called to be an apostle of Jesus Christ through the will of God, and Sosthenes our brother, Note that “to be” is added in the...