-toleana hadithi, 'tell each other a story' is a definition from Kiswahili: Msingi wa Kusema, Kusoma, na Kuandika by Thomas J. Hinnebusch and Sarah M. Mirza. So could this sentence possibly mean "We gave each other (exchanged) books outside?" Also, I can't recall for certain, but it seems to me I might have heard or seen the phrase "-toleana zawadi" (give each other presents) somewhere.
Doesn't -toleana come from -tolea which means "put forth" or "produce for". And tolea comes from -toa which means "to produce/call for/evoke"? Would this more naturally translate as "we put forth each other's books outside"? I mean, it still doesn't really sound too natural for me, but is that maybe a little closer to the meaning of -toleana?