To accelerate literacy learning for upper-elementary multilingual children designated as English learners (ML-ELs), teachers need instructional tools that create sustained opportunities for reading and discussing informational texts, examining the language encountered in those texts, and building new content knowledge. To address this need, we developed a multicomponent small-group intervention to build ML-ELs' reading comprehension by emphasizing knowledge, language, and structured inquiry (K.L.I.). We describe our iterative design process and report findings related to usability, which we argue is an essential but often unreported step in examining the internal logic of new interventions. Using design-based research, we developed K.L.I. through repeated design-implement-observe-revise cycles in collaboration with fifteen teachers over two years. We analyzed teacher interviews and ratings of lessons implemented during afterschool supplemental instruction. Findings suggest pressure points and enhancing factors affecting the usability of K.L.I. These findings can inform future efforts to design and implement similar multicomponent reading comprehension interventions. [This paper was published in "AERA Open" 2025.]