Really appreciate this breakdown. The three-layer model clears up a lot of the confusion around tools versus MCP versus skills. One thing I would add is that in practice, the boundaries get blurry at the edges. When a skill references a tool by name, it effectively becomes a routing layer, and MCP servers that return tool schemas dynamically are doing something closer to skill work than tool work. The real value of separating them becomes clear at scale: you can version your MCP servers independently from your tools, and your skills independently from both. That decoupling is what makes agent systems maintainable beyond a handful of functions. The tradeoff nobody talks about is latency. Every layer adds a round trip, and in a tight loop, those microseconds add up. Would love to see benchmarks comparing a single-tool MCP call against a native tool call in the same framework.