| Question | Skill | MCP |
|---|---|---|
| What it gives Claude | Know-how: your steps, rules and examples | Access: live data and actions inside another app |
| What it is | A folder with a SKILL.md file, sometimes with scripts | A connector that speaks one shared protocol |
| Who makes it | Anyone who can write the process down | Usually the app’s maker or a developer. You switch it on and log in |
| While it’s not in use | Only a short description sits in Claude’s view | Its tool descriptions can take up room in every conversation |
| How it breaks | Your process changes and nobody updates the file | The login expires or the app changes underneath it |
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Do I need both?
Often, yes, because most real jobs fetch something and then do something with it. My morning dashboard is a good example.
On my Mac, every scheduled job is a SKILL.md file. This one says what goes on the dashboard, in what order, and what counts as a red flag.
The connections fetch my tasks, my calendars and my screen time.
When I cancelled my old task app in August, the fix was to swap one connection for another.
The instructions barely changed. That’s the split working as it should: the know-how stays put while the plumbing changes.
One warning from the same job. It once stopped running without a sound. The folder was still on disk, so it looked scheduled.
It wasn’t. Neither a skill nor a connection checks that the work actually happened. Something else has to.
Which should I set up first?
The skill. Or really, the writing. Most people want to connect everything on day one.
I’d write down one job you repeat, then run it by hand with the information pasted in. You’ll find out what the job really needs. Then connect only that.
The exception is a job that is mostly fetching, like pulling yesterday’s sales.
There’s nothing to teach until Claude can see the numbers, so the connection comes first.
Can a skill replace an MCP server?
Sometimes. If a tool has a command-line program or a simple API, a skill can tell Claude how to use it directly.
Simon Willison made this point when skills launched: a lot of what people use MCP for can be a short instruction file plus a tool Claude already knows how to run.
My own notes work this way. They’re plain Markdown files in one folder, and my agents read them straight off disk. No server in between, nothing to log in to.
For apps that need you to sign in, like email, calendars or ad accounts, use a proper connection.
Approving access through the app is safer than handing a script your password.
You don’t need either to start. AI Foundations begins with your business context and one reusable instruction, which is the seed of a skill.
More on each side: what Claude skills are and what MCP is.
Sources: Claude Help Center: What are skills? · Simon Willison on skills and MCP