Grasslands support the majority of global livestock production systems while providing vital ecosystem services. Expansion of the livestock sector over recent decades has however placed enormous pressure on grasslands, with increasing greenhouse gas emissions that challenge the aspirations of climate mitigation. Here, we reviewed (a) climate policies pertaining to livestock and grasslands underpinning the Nationally Determined Contributions (NDCs) of 16 countries or regions, and (b) representation of grassland and livestock sectors in five contemporary integrated assessment models (IAMs). We find that mitigation policies reported in NDCs and Biennial Update/Transparency Reports (BURs/BTRs) remain limited in their specification of clearly defined forward-looking quantitative mitigation targets for ruminant livestock and grassland systems, despite their substantial contribution to agricultural emissions. At the same time, many reported policies are articulated in ways that support inventory-compatible, retrospective accounting. Contemporary IAMs, however, employ a highly simplified and aggregated representation of grassland–livestock interactions, with limited consideration of management intensity, degradation, restoration, and management-induced carbon dynamics. Taken together, these features reveal an information imbalance at the interface between policy articulation and model-based quantitative assessment, which may limit the transparency and cross-country comparability of evaluations of mitigation pathways in grassland and ruminant livestock systems.