Error Message: An object reference is required...

An object reference is required for the non-static field, method, or property 'tool.toolpos'

Hey, I'm getting this strange error message, and I can't find any conclusive support. Would you guys mind taking a look at my code? Thanks.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 using UnityEngine;
 using System.Collections;
 
 public class tool : MonoBehaviour
 {
     public Vector3 toolpos;
     public bool grabbed = false;
 
         // Use this for initialization
         void Start ()
         {
             
         }
     
         // Update is called once per frame
         void Update ()
         {
         toolpos = this.gameObject.transform.position;
         }
 }