This study mapped the distribution of validated Health Literacy (HL) assessment tools by age group using data from the Health Literacy Tool Shed. A documentary and quantitative analysis classified instruments for children, adolescents, adults, and older adults. Among 225 tools, most targeted adults (63.2%), followed by older adults (20.8%) and adolescents (14.4%), while children were minimally represented (1.6%). This imbalance limits early HL assessment and the design of age-appropriate interventions. Identifying these gaps highlights the need to develop and validate tools for younger populations, supporting more equitable measurement and practical strategies to strengthen HL across the life course.