What tools are available to auto-produce documentation for a REST API written in Flask? [closed]

I would recommend you Sphinx, you add your documentation as __doc__ and the autodoc module of Sphinx will generate the docs for you (docs.python.org also uses Sphinx). The markup is reStructuredText, similiar to Markdown (if you prefer Markdown, you can use pdoc).

e.g.:

@app.route('/download/<int:id>')
def download_id(id):
    '''This downloads a certain image specified by *id*'''
    return ...