Agent Harness vs Agent Framework vs MCP: Which Layer Owns the Loop, State, Tools, Permissions, and Recovery

Harness, framework, and MCP get used interchangeably in agent architecture discussions. They are not the same thing. They sit at different layers, own different responsibilities, and increasingly overlap at the edges. This article separates the 3 with 1 question. Which layer owns the execution loop, state, tool transport, permissions, and...