What is Jamies description in the mixed up files of Mrs basilE frankweiler?

In "From the Mixed-Up Files of Mrs. Basil E. Frankweiler," Jamie Kincaid is described as being a very organized and practical 12-year-old boy who is always thinking logically and planning ahead. He is level-headed and responsible, balancing out the more impulsive and imaginative qualities of his sister, Claudia.