I was building an MCP server for an event platform that automates speaker communications (confirmations, reminders, calendar invites, follow-ups). An agent created a session confirmation for "Monday March 8th." March 8th was a Sunday. I caught it. But catching it was just the beginning. The confirmation email had already been drafted with "Monday March 8th." The calendar invite had the wrong day. The follow-up survey was timestamped against a date that didn't exist on the schedule. One silent error had propagated into every downstream artifact the system touched. Now I'm not fixing one mistake. I'm chasing it through four different outputs, correcting each one, regenerating, re-checking. Every correction creates noise. Every re-check takes time. And the whole time I'm wondering: what else did it get wrong that I didn't catch? That's the thing about silent errors. They don't announce themselves. They don't crash. They just quietly spread, and the cleanup costs more than the original task saved you.…