Similarly to how the Constitution of the United States requires the US president to deliver a State of the Union address to the US Congress, Article 98 of the UN Charter requires the secretary-general to "make an annual report to the General Assembly on the work of the Organization."
Some of the times it has been invoked include: Kofi Annan expressed reservations about using Article 99, because it can make the secretary-general take a political role instead of an administrative one.
[2] Article 100 stipulates the independence and impartiality of the secretary-general and other staff members, stating that they "shall not seek or receive instructions from any government or from any other [external] authority".
Similarly, it requires the member states to "respect the exclusively international character of [the staff's] responsibilities" and to refrain from seeking to influence them.
Due regard shall be paid to the importance of recruiting the staff on as wide a geographical basis as possible."