Measurement system capability analysis (MSCA) is vital for enhancing process and quality performance, yet its use when the system is defined by a simple linear profile (SLP), has not been investigated. Existing studies on SLP MSCA primarily concentrate on profile parameters, establishing precision-tolerance ratio (PTR) criteria for both intercept and slope but neglect the critical influence of specification limits (SLs) on PTR accuracy. This paper presents a novel evaluation framework for SLP measurement systems. By introducing a new method for calculating SLs for profile parameters, the study proposes a modified PTR criterion and extends process capability indices (PCIs) for measurement profiles. Compared to existing approaches, our proposed indices enable a more accurate and comprehensive assessment of measurement system performance by incorporating both accuracy and precision, as well as appropriately determined SLs for profile parameters. A case study in spring manufacturing validates the effectiveness of these indices in industrial contexts.