The assumption that Snorri Sturluson is responsible for writing the Prose Edda is largely based on the following paragraph from a portion of Codex Upsaliensis, an early 14th-century manuscript containing the Prose Edda:
This book is called Edda. Snorri Sturluson compiled it in the way that it is arranged here. First it tells about the Æsir and Ymir, then comes the poetic diction section with the poetic names of many things and lastly a poem called the List of Meters which Snorri composed about King Hakon and Duke Skuli.
It has been noted that this attribution, along with other primary manuscripts, are not clear whether or not Snorri is more than the compiler of the work and the author of Háttatal or if he is the author of the entire Prose Edda. Whatever the case, the mention of Snorri in the manuscripts has been influential in the acceptance of Snorri as the author of the Prose Edda.