Look at where each one is set in the UI of Glyphs. For example, ascender and descender are per master, so you would set that for the master. Take a look at https://docu.glyphsapp.com/#gsfontmaster
Others may be set as customParameters in the appropriate spot, e.g., master, instance, font. Untested code follows:
font = Glyphs.font
master = font.masters[0]
master.ascender = 870.0