If you expand your scope a bit from just developer tooling, you’ll notice a lot of scenarios where an agent running somewhere as a service may need to invoke commands elsewhere, in other apps, or maybe provided by a customer in a bring-your-own-MCP setup. In these cases, the harness is not running locally, you don’t have a filesystem to write skills on demand to (or a fixed set of skills is baked into the container), so to get extensibility or updates to tooling, you want something that avoids redeployments. MCP fills that spot.