Both- depending on the work. CLI for anything local and deterministic: code tools, builds, git, file ops. The agent already knows how to exec commands and parse output, and when something breaks you get stderr and an exit code. MCP for discovery and remote services where the agent needs to figure out what's available.
They solve different problems, but imo MCP has a speed overhead problem that cli tools don’t usually have - so my preference is CLI.
They solve different problems, but imo MCP has a speed overhead problem that cli tools don’t usually have - so my preference is CLI.