You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Sino-Tibetan_relations_during_the_Ming_dynasty

Context:
Marsha Weidner states that Deshin Shekpa's miracles "testified to the power of both the emperor and his guru and served as a legitimizing tool for the emperor's problematic succession to the throne," referring to the Yongle Emperor's conflict with the previous Jianwen Emperor. Tsai writes that Deshin Shekpa aided the legitimacy of the Yongle Emperor's rule by providing him with portents and omens which demonstrated Heaven's favor of the Yongle Emperor on the Ming throne.

Question:
What served as a legitimizing tool for the emperor's succession to the throne?

Deshin Shekpa's miracles