Scotland's only try came from Lucia Scott and was converted by Lucy MacRae.
The Scots enjoyed their fair share of territory and possession in the first half but a try from Sophie Barrett, alongside a conversion and two penalties from Kate Flannery, gave Ireland a 13-0 lead.
Scottish pressure finally told when Scott sprinted through the Irish line to score.
MacRae's conversion from wide on the right and meant Scotland were only six points behind at half-time.
Beth Buttimer's second-half hat-trick allowed Ireland to pull away, before Hannah Wilson's try a few minutes from time.
The tournament has been a testing development experience for the players but they've shown enough across their three fixtures to be optimistic about the talent Scotland has coming through.