Financially constrained governments, particularly in emerging and developing economies, tend to face a fiscal trade-off between adapting to climate change impacts and pursuing broader development goals. This trade-off is especially relevant in the agriculture sector, where investing in adaptation is critical to ensure food security amidst climate change. International trade can help alleviate this challenge and reduce adaptation investment needs by offsetting agricultural production shortages. However, in the presence of trade fragmentation, the adaptive role of trade diminishes, exacerbating food insecurity and increasing investment needs for adaptation. In this paper, we present a model to guide policymakers in deciding on the cost-efficient balance between investing in adaptation in the agricultural sector versus in broader development under financing and trade constraints. We apply the model to Ghana, Egypt, and Brazil, to examine the adaptation-development trade-off and highlight factors that would potentially lower adaptation investment needs. These factors include trade openness, higher agricultural productivity and efficiency of adaptation spending, and reduced labor market distortions. The key takeaways from the model applications suggest that (i) promoting trade openness and accessing concessional finance for adaptation help tackle climate challenges and ensure food security in lower-income countries; and (ii) domestic structural reforms are necessary to facilitate adaptation investments and reduce investment needs, by improving labor market flexibility, adaptation efficiency, and agriculture productivity.