The latest Model Context Protocol introduces Output Schema: agents now know the exact data structure a tool will return before calling it.

This eliminates the "print-and-inspect" pattern where CodeAct agents call tools just to discover what data they get back. Instead of multi-step exploration, agents can write complete, precise programs from the start.

What's new: Tools declare their output schemas upfront

What's better: Agents plan complete execution paths instead of reactive discovery

Now supported in Hugging Face smolagents.