In Hubspot, there is the feature to add tags to articles. The idea being that the tag will help associate users and visitors to your knowledgebase to the right articles. It should also improve the accuracy of your chatbot's KB lookup.
In regards to the articles that are shown, the title of the articles is given preference over the tags. This is odd given you've gone through the effort of manually tagging articles, ensuring the article is exactly the right one based on the keywords the visitors has used.
The chatbot's Knowledgebase lookup is affected worse so, because it is limited to 3 results. If you have articles like "how do I..." and the customer enters those words, the chatbot will pick up random articles with the title starting "how do I..." rather than the rest of the query "how do I log in to my account".
Give tags a higher priority than title.