Skill, MCP, Plugin, or just a CLI: how I pick a Claude Code extension, lightest first

I was building a plugin release with Claude Code, and the changelog draft came together nicely. Pull git log from the last tag to now, drop it under == Changelog ==. That's a procedure, so it just worked. The next step is where I tripped. I wanted to add the current WordPress.org active install count to the release post, so I added a line to the same procedure file: "fetch the stats and write them in." It didn't work. Of course it didn't. A file that holds a procedure teaches Claude the steps, but it has no legs to go out and fetch today's numbers from a website. To go get them, you need a mouth that talks to the outside. That was a different tool's job. Claude Code has several ways to add capability: Skill, MCP, Plugin. The names sound alike and the explanations blur together, and a CLI is in the mix too. I build WordPress plugins and use coding agents most days, and I still hesitated every time about which one to reach for. This post is how I draw the line, settled into one rule: r