Why AI agents fail at scheduling (and how to fix it)

Your AI agent can draft emails, search the web, summarize a 40-page PDF, and write code. Then someone asks it to "find a time with Sarah and James next week" and it confidently books a slot during Sarah's all-hands meeting. This isn't a reasoning failure. The LLM didn't get confused. It's an API design problem — calendar APIs were built for humans navigating UIs, not for agents making sequential tool calls. And the gap between what those APIs expose and what an agent needs to do reliable scheduling is wider than it looks. The real reason: calendar APIs aren't built for agents To find mutual availability for two people using raw Google Calendar or Outlook, an agent has to: Authenticate with OAuth for each person (more on this in a moment) Fetch each person's calendar events for the target week Parse the free/busy data into usable windows Cross-reference working hours per timezone Apply buffer preferences (no back-to-back meetings, no 8am calls) Rank the resulting slots by quality Handle