Your MCP server can't take a file as an argument — here's why, and the fix

I built an MCP server that publishes HTML files, and I hit a wall I haven't

seen documented anywhere: you can't pass a large file as an MCP tool

argument. Not "it's slow" or "it's awkward" — the model is physically

incapable of doing it.

Here's the failure, why it happens, and the one-line design change that fixes it.