# The Orchestrator in Multi-Agent Systems: The Brain # Nobody Talks About But Every System Depends On

Table of Contents What an Orchestrator Actually Is The Four Core Responsibilities How Orchestrators Communicate With Agents The Three Orchestration Architectures Information Flow: Top-Down, Bottom-Up, and Lateral What Breaks in Production and Why The Evolving Orchestrator: What 2025 Research Proved Human Oversight as an Orchestration Function Protocols: Where MCP and A2A Fit The Decision Framework for Architects 1. What an Orchestrator Actually Is An orchestrator is not an agent that does work.