Genesis 15:6 :
... and he counted it to him for righteousness. KJV.
... and He reckoneth it to him -- righteousness. Young's Literal.
... And He counted it to him for righteousness. Green's Literal.
The word chashab ('counted' 'reckoned') only has the count/reckon meaning in the Niph homonym form and that form is a passive form (Young's Analytical Concordance) so would be 'be counted' or 'be reckoned'.
The Septuagint has :
kai elogisthe autw eis dikaiosunen
and those exact words are used by Paul in Romans 4:3, Romans 4:22 and Galatians 3:6, then by James in James 2:23.
Logizomai (from which is the inflected form elogisthe) is a deponent verb and the translation of it is therefore a passive rendering . . .
... and it was counted unto him for righteousness. Romans 4:3 KJV.
Is the Septuagint (from which, presumably, Paul and James are quoting) a more accurate rendering of the passive verb in Genesis 15:6 than the English renderings of the Hebrew ?