You need to know why your commitment to me takes priority over other demands. Negotiate commitments in good faith. A commitment which is coerced, made in haste, or made under duress is weak at best. You will feel more accountable for commitments you have made thoughtfully and with free will. Communicate commitments thoroughly.
Ambiguity kills accountability.
As a leader, It is my responsibility to make sure I understand exactly what you believe your commitment to be. Respect reasonable assumptions. Commitments are always made within the context of assumptions. I must understand the context within which you have made your commitment. Defend the scope of commitments.