Your MCP server can't take a file as an argument — here's why, and the fix
A developer encountered a limitation when building an MCP server, discovering that large files cannot be passed directly as arguments to model tool calls. This is because tool arguments are part of the model's output, which is constrained by maximum output tokens, making it impossible to transmit large files. The solution involves modifying the tool to accept a file path instead of the file content, allowing the server to read the file from disk and perform operations like uploading it. AI
IMPACT Developers using tool-calling models must pass file references, not raw file data, to avoid token limits and ensure functionality with large artifacts.