Passing values through the pipeline question

Hi all,
I am sorry to post a question that may be easily tested, but I don’t have an OGL4+ hardware at the moment.

Looking at various tutorial that involve tessellation shaders, each single parameter that I want to send from the texture shader to the fragment shader are before passed through tessellation shaders as well (as they always needed in the case I saw).
If I have a variable that I want to send from vertex shader to the fragment one, but that’s not needed by TCS and TES, can I just do something like

//// Vertex shader

out vec3 foo;

// Ignore foo in tessellation control and eval shader

//// Fragment shader
in vec3 foo; 

or I have to pass foo through the tessellation shaders as well?

Thank you!