public class Foo {
    public List<Tuple<string, string, bool>> Items { get; set; }

    public Foo()
    {
        Items = new List<Tuple<string, string, bool>>();
    }

    public override string ToString()
    {
        StringBuilder sb = new StringBuilder();
        foreach (var a in Items)
        {
            sb.Append(a.Item1 + ", " + a.Item2 + ", " + a.Item3.ToString() + "rn");
        }
        return sb.ToString();
    }
}

[TestClass]
public class NormalTests
{
    [TestMethod]
    public void TupleSerialization()
    {
        Foo tests = new Foo();
        tests.Items.Add(Tuple.Create("one", "hehe", true));
        tests.Items.Add(Tuple.Create("two", "hoho", false));
        tests.Items.Add(Tuple.Create("three", "ohoh", true));

        string json = JsonConvert.SerializeObject(tests);
        Console.WriteLine(json);

        var obj = JsonConvert.DeserializeObject<Foo>(json);
        string objStr = obj.ToString();
        Console.WriteLine(objStr);
    }
}

var testTuple = Tuple.Create(1234, "foo", true);
var serialized = JsonConvert.SerializeObject(testTuple);

Console.WriteLine(serialized);
// prints: {"Item1":1234,"Item2":"foo","Item3":true}