The short distinction
A skill is procedural knowledge. MCP is an integration protocol. If an assistant needs to know how to review a pull request, a skill can define the method. If it needs repository data or an action exposed by another system, an MCP server can provide that capability.
What a Claude skill controls
A skill can describe when to activate, what inputs are required, the ordered reasoning process, output structure, safety constraints, and known limitations. It is primarily readable instruction content, often centered on a SKILL.md file with optional references, templates, or scripts.
The code-review assistant skill, for example, can define the dimensions and severity language of a review. It does not automatically grant access to a private repository. Access must come from the host environment or an integration.
What MCP controls
MCP defines a client-server model for exposing tools, resources, and prompts to compatible AI applications. A server can describe what capabilities are available and accept structured calls. Authentication, deployment, and permissions remain implementation concerns; using MCP does not make an integration safe by itself.
The API integration architect skill can help plan authentication, retries, webhook verification, and least-privilege scopes. An MCP server may implement part of that connection layer, while the skill provides the method used to reason about it.
How they work together
Imagine a support-triage assistant. An MCP server exposes ticket search and update tools. A skill tells the assistant how to classify urgency, identify missing information, draft a response, request approval, and decide whether an update is appropriate. The MCP layer supplies capability; the skill supplies operating procedure.
Keep them separate when possible. Tool schemas should remain deterministic and narrowly permissioned. Skills should avoid hard-coding undocumented endpoints or assuming every environment exposes the same tool. This separation makes both layers easier to test.
Which one should you build first?
Write a skill first when the task can already be completed with information the user provides and the main problem is consistency. Build or configure an MCP connection when the assistant needs live external context or actions not otherwise available. Often the safest sequence is to prove the workflow manually, document it as a skill, then add the minimum necessary integration.
Read what a SKILL.md file is for the instruction layer and explore real Claude skill examples before adding tools.