Developer fixes MCP tool that sent empty API updates with no fields to change

A developer discovered a logic gap in an MCP server tool called update_article, which manages posts on the DEV.to platform. The tool, designed to update article fields like title, body, or publish status, allows all optional parameters to default to None — but never checks if all three are simultaneously absent. When called with only the required article ID and no other arguments, the function still fetches the existing article, sends an empty PUT request to the live API, and writes an audit log entry showing zero fields changed. Previous hardening efforts had added a fetch-before-write step and a JSONL change log to prevent silent overwrites, but both assumed at least one field would always be provided. The fix required adding an early exit condition to reject calls where no fields are specified, closing a gap that could be triggered accidentally by AI agents passing incorrect or missing arguments.