Background As the mental health consequences of climate change become increasingly visible, eco-anxiety and related responses, such as climate distress are emerging as critical areas of research. Many measurement tools now exist, but questions remain about their conceptual clarity and cross-cultural relevance, especially in low- and middle-income countries (LMIC). This rapid review synthesised survey-based instruments assessing these constructs, focusing on their cross-cultural relevance. Methods A systematic search of 10 databases identified peer-reviewed studies published between January 2019 and February 2025 reporting the development, validation, translation, or adaptation of tools measuring eco-anxiety or related constructs. Data were synthesised narratively, alongside an AI-assisted thematic content analysis of questionnaire items examining constructs, focus of concern, and cultural adaptability. Results Seventy-three studies were included, covering 23 measurement tools and 297 questionnaire items, predominantly developed in high-income countries and validated with university students or online adult samples. Several tools have multiple translations, yet formal cross-cultural validation in LMIC is limited. Emotional responses (e.g. anxiety, sadness, grief ) dominated (65.3% of items), followed by cognitive responses such as worry and rumination (21.5%) and moral or value-based distress (15.8%); somatic and existential dimensions were rarely assessed. Most items focused on personal concerns (71.0%), with fewer addressing social (22.2%), global/ecological (11.8%), or local place-based (6.7%) dimensions. Over half of items were generally interpretable across cultures, but one in seven embedded value-contingent moral assumptions such as personal guilt (15.5%), and a similar proportion implicitly assumed conditions, such as regular media exposure to the climate crisis, consumer choice, and individual environmental agency (14.5%). Conclusions Most instruments lack sensitivity to diverse cultural, social, and ecological contexts, overemphasising individual emotional distress while underrepresenting the relational, systemic, and place-based concerns most relevant in climate-vulnerable regions. Future tools should be co-developed with local populations to inform equitable global mental health responses to climate change.