Can Claude Send and Read Email Attachments? Yes, With No Base64 Encoding.
Ask an AI to email you a PDF and it either says it can't, or it starts typing the file out as base64 and runs out of reply. That is not the model being bad at files. MCP tool arguments are JSON, and JSON has no file type, so every server hits the same wall separately. Here is the gap in the spec, what base64 really costs (including the figure we published wrong for a month), and the four routes we built instead.