Hydrolyzes linear guanidino acids to form urea and the corresponding amines. Displays specificity for substrates having a negatively charged head group and short chains including taurocyamine, guanidino propanoic and butanoic acids. May protect cells by detoxifying potentially harmful amounts of guanidino acids. Metabolizes L-arginine with low efficiency. . This is the function of Ensembl gene identifier ENSG00000116771 (AGMAT, agmatinase (putative)).