Having implemented and used it, I like this setup so much it kinda ruined Claude.ai and ChatGPT.com for me
insin on Hacker News
450,000+ row spreadsheet
In the thread “Claude for Small Business”, replying to this comment
Helped: Local file access via folder picker and MCP for large data processing.
… Or go find the big 450,000+ row spreadsheet that's being automated somewhere on SharePoint, pull it down in 150,000 row chunks (Graph Excel REST API limit) and write code to go figure out whatever the user is asking. Having implemented and used it, I like this setup so much it kinda ruined Claude.ai and ChatGPT.com for me, so I've hooked up similar access for them using a browser extension to add the folder picker input, with the extension talking to a local server to tell it which folder to give access to, and Claude/ChatGPT talking to the same server over MCP via a CloudFlare Tunnel to work with the selected folder.