Claude Skills vs MCP: which one should you actually build?

Most explainers stop at one line: MCP is connection, Skills are instruction. That is correct, and it is not enough to decide what to build on a Tuesday afternoon.

This page is the decision version. You will get the short answer, a table that maps your actual situation to the right tool, two working examples, and the part nobody else covers: what to do once you have picked Skills and face forty thousand of them.

If you are brand new to the format, read what are Claude Skills first, then come back here to choose.

The one-sentence answer

An MCP server gives Claude access to something external. A Skill gives Claude a repeatable way of doing something. You reach for MCP when Claude needs to touch a system it cannot otherwise see, and for a Skill when Claude already has what it needs but keeps doing the task differently every time.

When both are true, you use both. The MCP server hands Claude the database connection; the Skill tells Claude how your team queries that database and what a good answer looks like.

What an MCP server actually is

MCP, the Model Context Protocol, is a connection layer. An MCP server exposes tools and resources that Claude can call: a row in Postgres, a file in a GitHub repo, an issue in Linear, a row in your CRM. Once the server is connected, that access persists across sessions. Claude can read and write to the system without you pasting context every time.

The key word is access. An MCP server does not teach Claude judgment. It opens a door. What Claude does once it walks through is a separate question.

What a Claude Skill actually is

A Skill is a directory whose only required file is SKILL.md. That file carries a trigger description, the procedure, and the shape of the output. Claude loads it on demand when a task matches the description, runs the steps, and returns the result in the format you specified.

The detail competitors skip: a Skill can carry deterministic code, not only prose. If the task has a step that should run the same way every time, you put a script next to SKILL.md and the Skill calls it. That is why Skills beat a saved prompt. A prompt is a wish. A Skill is a procedure with a fixed output.

A real SKILL.md, not an abstract one

---
name: weekly-revenue-digest
description: Summarize last week's revenue from the finance database.
             Use when someone asks for the weekly revenue digest.
---

# Weekly revenue digest

## Procedure
1. Query bookings, expansion, and churn for the last 7 days
2. Compare each against the prior 7 days
3. Flag any line that moved more than 15 percent
4. Format using the output contract below

## Output
**Week of {date}**
- New bookings: {amount} ({delta} vs prior week)
- Expansion: {amount} ({delta})
- Churn: {amount} ({delta})
- Watch: {one line on the biggest mover}

Notice what this Skill does not do: it does not know how to reach the finance database. That is the MCP server's job. The Skill assumes the connection exists and encodes the procedure on top of it. See more patterns in Claude Skills examples.

The decision table

Match your situation to the row. This is the part to screenshot.

Your situation	Build this	Why
Claude needs to reach a system it cannot see (database, repo, CRM, internal API)	MCP server	The problem is access, not instruction
Claude already has access but keeps doing a task differently each time	Skill	The problem is consistency, not connectivity
A task should run identically every time, including a deterministic step	Skill with a bundled script	Code in the Skill removes drift
Claude needs to reach a system and follow your team's exact procedure on it	Both	MCP opens the door, the Skill walks the path
You want the behavior to work across Claude Code, Codex, and Cursor	Skill	SKILL.md is portable; see the cross-vendor guide
You are pasting the same long prompt every session	Skill	A Skill is that prompt, made repeatable and triggerable

If you only remember one rule: connectivity points to MCP, consistency points to Skills, and most real work needs a little of both.

Using them together

The cleanest mental model is the hammer. MCP hands Claude the hammer. The Skill explains how to drive the nail. Here is a Skill that assumes an MCP server is connected and builds a procedure on top of it.

---
name: triage-new-bug
description: Triage an incoming bug report. Use when a new issue is filed
             or pasted in. Requires the Linear and GitHub MCP servers.
---

# Triage new bug

## Procedure
1. Search Linear for duplicates of the report (Linear MCP)
2. If a duplicate exists, comment with the new context and stop
3. Otherwise search the GitHub repo for the failing symbol (GitHub MCP)
4. Open a Linear issue with severity, the suspect file, and a repro
5. Return the issue link and your severity call

## Output
**Triage result:** {created | duplicate}
**Issue:** {link}
**Severity:** {sev} because {one line}

The MCP servers provide the reach into Linear and GitHub. The Skill provides the judgment: search before filing, dedupe first, set severity with a reason. Neither tool does the other's job, and together they do something neither can alone.

The question nobody answers: once you pick Skills, which Skill?

Say you have made the call. Your task is about consistency, so you want a Skill. Now you hit the real wall.

There are more than forty thousand Skills across Anthropic, the community marketplaces, GitHub, and a half-dozen vendor directories. Quality is uneven. Half of them are saved prompts wearing a SKILL.md costume. Discovery is a mess, and trust is worse: you cannot tell from a name whether a Skill is sharp or whether it will quietly drift the first time an input changes.

This is the problem that appears after the Skills-vs-MCP decision, and it is the one implexa exists to solve. A skill graph indexes Skills across every vendor, and SkillRank scores them so you install the one that actually works instead of the one that ranked first alphabetically. Picking Skills over MCP is the easy half. Picking the right Skill is where most people lose the week.

If you would rather write your own, the step-by-step guide walks through all six components. And if you are worried about loading too many, how many Claude Skills is too many covers the context budget.

FAQ

Can a Skill use an MCP server?

Yes, and this is the common case. A Skill encodes a procedure that calls the tools an MCP server exposes. The MCP server provides access to the system; the Skill provides the steps and the output format. They compose cleanly because they solve different halves of the problem.

Do Skills replace MCP?

No. They are not substitutes. MCP is how Claude reaches a system it cannot otherwise see. A Skill is how Claude does a task the same way every time. If your problem is connectivity, no amount of Skills will help, and the reverse is also true.

Are Claude Skills cross-vendor?

Skills are portable because SKILL.md is plain markdown with a trigger description. The same Skill can run in Claude Code, Codex, and Cursor. MCP is also an open standard, so connected servers carry across compatible clients too. See the cross-vendor guide for the details.

Which is faster to set up?

A Skill is usually faster: write a SKILL.md, drop it in your Skills directory, done. An MCP server takes more work because you are wiring a real connection to an external system, with auth and permissions. If your task does not need external access, a Skill avoids that setup entirely.

When should I build both?

When Claude needs to reach a system and follow a specific procedure on it. Connect the MCP server for access, then write a Skill that assumes that access and encodes how your team works on top of it. The bug-triage example above is exactly this shape.

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The short version: connectivity is an MCP question, consistency is a Skills question, and the hard part is not the choice but finding the Skill that earns its place. Start at the Claude Skills pillar if you want the full map.