Support more tools for complex tasks

[mondaychen]

Depended on #53

This would enable interesting workflows like "post a meme picture about workaholic in this slack chat"

New tools like

• get & save summary of page (news article, blog, etc.) (maybe can use https://github.com/mozilla/readability)
• get & save a image

New memory

• observed pages and their tab id

Note: before working on this, create individual issues and use this as parent