How to set hovertools in Bokeh with pandas dataframe column

Question

So this is my first real python project and its got a few parts:

1) Use tweepy to retrieve a JSON object from Twitter's API

2) Use pandas to assign JSON values to data frame columns

3) Create a bokeh scatterplot with hovertools from that data frame

I keep on getting this error message when I try to create the plot in Bokeh:

TypeError: {....} is not JSON serializable

Isn't the data "non-JSON" since it's in a data frame? Would I need to convert the data frame columns I'm using to a dictionary first beforehand? My code with brief comments is below:

from bokeh.plotting import figure, output_file, show, ColumnDataSource
from bokeh.models import HoverTool
import tweepy
import pandas as pd


CONSUMER_KEY = ''
CONSUMER_SECRET = ''
ACCESS_TOKEN = ''
ACCESS_TOKEN_SECRET = ''

auth = tweepy.OAuthHandler(CONSUMER_KEY, CONSUMER_SECRET)
auth.set_access_token(ACCESS_TOKEN, ACCESS_TOKEN_SECRET)
api = tweepy.API(auth)

#set up search
results = []
for tweet in tweepy.Cursor(api.search, q = '#twitter').items(100):
    results.append(tweet)

#set up dataframe
id_list = [tweet.id for tweet in results]
data_set = pd.DataFrame(id_list, columns=["id"])

#tweet data
data_set["text"] = [tweet.text for tweet in results]
data_set["retweet_count"] = [tweet.retweet_count for tweet in results]
data_set["source"] = [tweet.source for tweet in results]


output_file("toolbar.html")

#set data source  
source = ColumnDataSource(data=dict(x=data_set['source'],y=data_set['retweet_count'],desc=data_set['text'))

#create hover tool object 
hover = HoverTool(
        tooltips=[
            ("index", "$index"),
            ("(x,y)", "($x, $y)"),
            ("desc", "@desc"),
        ]
    )

#set plot parameters 
p = figure(plot_width=400, plot_height=400, tools=[hover],
       title="Mouse over the dots")

p.circle('x', 'y', size=20, source=source)

show(p)