Showing the answer
An answer is a list of parts. A part is text, HTML or an image.
Text
Text is Markdown. Every chat application uses its own dialect, so convert it. Slack and Google Chat need bold and links rewritten. Teams accepts a wider subset.
Images
An image arrives base64 encoded, with its MIME type. Upload it with the chat application's own file API.
HTML
HTML has no equivalent in Slack, Teams or Google Chat. Convert it to text, or tell the person that the answer is available in the UI. An agent written for a chat audience should produce text and images.

