Ka kammala wannan furcin: An rubuta waƙoƙin Seixas don kaɗe-kaɗe dabam-dabam, har da garaya, da kuma clavichord. Duk da haka, a cikin salon magana, sonatas ya nuna nau'o'in nau'o'in kiɗa: wasu suna da misali na Baroque toccata; wasu suna da tabbaci a cikin salon salon; wasu suna da tasiri sosai daga Jamusanci "Empfindsamer Stil" (a zahiri'mai hankali style'). Duk da cewa ba kasafai ba, idan har abada, ya yi tafiya a waje da Lisbon, aikinsa ya haɗa da nau'ikan yanayin ƙasa daban-daban, kamar makarantar Mannheim ta Jamus, da minuet na Faransa, da kuma salon Italiyanci kamar yadda Scarlatti ya tsara, abokin aikinsa kuma mai zamani. Santiago Kastner, Seixas's biographer da kuma editan ayyukansa, ya bayyana ayyukan Seixas a matsayin "marasa aiki" tare da wani nau'i na musamman, kuma an ba da shi ga sau da yawa. Yawancin ayyukansa sun lalace a cikin
girgizar ƙasa da ta halaka Lisbon a shekara ta 1755. Abubuwa uku ne kawai na ƙungiyar makaɗa da kusan ɗari ɗari na sonatas na keyboard daga cikin sama da ɗari bakwai da aka yi da'awar sun tsira, tare da wasu ayyukan waƙa don amfani da liturgical (mafi yawanci fiye da abin da mutum zai yi tsammani daga waƙarsa ta kayan aiki).