This is the proviso that Mr Mitchell, prolific poet and playwright, has put forward in Daft as a Doughnut, his new book for children.
Preceding a dedication to his eight grandchildren, and underneath an illustration of a startled-looking teacher, the 72-year-old states: "GOOD LUCK, TEACHERS! Please don't use these poems or any of my other work in exams or tests."
The reservation reflects a lifelong belief that exams hinder children's enjoyment of learning. He told The TES: "Education should be about enjoyment. If there's no enjoyment, you may as well close down the school.
"I do want my poems to be used in schools. I want pupils to read them, act them, sing their own versions. But I don't want them to have to write boring essays analysing them. I'm against the vivisection of poems that goes on in exams."
Instead, Mr Mitchell believes that children learn better by reading about subjects that interest them. In his youth, he drew up his ideal timetable, made up of history, writing and aircraft-spotting, and no maths.
"Children aren't told that going to school is optional," he said. "Children should learn at their own pace. They shouldn't be taught, this is a haiku, this is a limerick. They should think about which poems make you laugh, which make you cry, which affect your life."
Mr Mitchell, who decided against a career in teaching because he felt class sizes were too large, is not the first author to speak out against school exams. In 2003, more than 80 children's authors and illustrators, including Michael Morpurgo, Philip Pullman and Ros Asquith, called for an end to national tests.
Mr Morpurgo, the children's laureate, has said that compulsory testing during his own schooldays came close to killing his love of literature.
He said: "No Shakespeare play touched me, no Hardy novel, no Dickens novel.
I read them because I had to, because I was going to be tested on them."
Exam boards ask permission from authors or their publishers if they intend to use extracts in an exam question. The OCR board pays authors for extracts but Edexcel only uses work from authors who do not ask for payment.