This paper discusses the design and evaluation of a set of heuristics (U + A) to assess the usability and accessibility of interactive systems in terms of cognitive diversity in an integrated way. Method: An analysis of the usability and accessibility aspects that have the greatest impact on people with cognitive disabilities is presented. A set of cognitive usability and accessibility heuristics targeted at people with cognitive disabilities is generated with the support of generative artificial intelligence (GenAI). Result: Several interactive systems are evaluated to validate the U + A heuristics. A quantitative classification of the evaluated systems is obtained, i.e., the “U + A-index”, which reveals the most and least usable and accessible systems for people with cognitive and learning disabilities. Conclusions: This study demonstrates that it is possible to carry out a classification of heuristic criteria considering accessibility, usability, and cognitive disability. The results also show that the selection of criteria proposed by GenAI is optimal and that this technology can be used to improve usability and accessibility of interactive systems in a practical way. Yet, further evaluations are needed to support the results of the analyzed proposal.