Plus You're likely building an API already if you have an MCP. Not everyone using MCP is a dev, we have random corporate workers using our MCP. They don't know what an API is but they can add a plugin from an agent marketplace (which can also contain skills) and MCP is a bit narrower with a clear authorization system, tool discovery, and annotations (agents ask "confirm you want you want to write this").

Just give your end-users flexible options. If they have Claude Code then build more around the API side if needed.