I've created a Chrome extension and Node.js server combo that lets Claude use external tools (calendar, Spotify, etc.) from within regular browser conversations - without any API access.
## Why
Tool use is available in Claude via API, but I haven't found a way to use tools from the web interface.
Over a weekend I've created a PoC and spent the next few weeks polishing the details before sharing.
The architecture is modular, making it easy to add new tools. I've included detailed setup instructions in the repo.
## How it works
- The extension injects a content script onto claude.ai/chat pages
- A background script captures all Claude responses via Chrome debugger API
- When Claude generates XML tool tags (e.g., <calendar>...</calendar>), the server executes the corresponding action
- Results appear as system messages that you can paste into your conversation, so that Claude is aware of failures etc.
Demo video: https://www.youtube.com/watch?v=j8lgsGurY1w
GitHub: https://github.com/BartlomiejLewandowski/claude-browser-tool...
## Tools currently supported
- Google Calendar (create events)
- Spotify (play music)
Would love feedback on the approach and ideas for other useful tools to add!
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