Claude Skills and MCP solve different layers of a problem
A Skill primarily supplies instructions: the procedure, constraints, examples, references, or scripts Claude should use for a recognizable task. MCP is a client-server protocol for exposing capabilities such as tools, resources, and prompts to an AI application. One guides the work; the other can connect the application to systems where work happens.
The distinction matters because a workflow can be useful without external access, and a tool connection can be available without explaining the best process for using it. Neither mechanism automatically replaces the other.
Claude Skills vs MCP comparison
| Dimension | Claude Skill | MCP |
|---|---|---|
| Primary purpose | Package reusable instructions and task resources | Connect an AI application to external capabilities |
| Main unit | A skill directory centered on SKILL.md | A client connection to an MCP server |
| External data or tools | Optional; instructions may use tools already available | Core use case; servers expose tools, resources, or prompts |
| Setup | Place or install a reviewed skill package | Configure a server, transport, capabilities, and often authorization |
| Execution | Claude loads instructions and follows them with available capabilities | Client discovers server capabilities and can call defined operations |
| Portability | Agent Skills defines a cross-tool package format; hosts may add extensions | MCP is an open protocol supported by multiple clients and servers |
| Maintenance | Update instructions, tests, scripts, and references | Maintain server code, schemas, auth, dependencies, and compatibility |
| Typical risk | Unsafe instructions, scripts, excessive tool grants, stale guidance | Credential exposure, over-broad access, untrusted servers, authorization flaws |
When a Skill is enough
Use a Skill when the essential value is a repeatable method and the required information is already in the conversation, repository, or local environment. Examples include reviewing code against a checklist, applying an editorial style, producing a standard incident summary, or following a repository's release verification steps.
A skill may call existing tools or run a reviewed bundled script, but it does not create a new interoperable service connection by itself. If the procedure only needs files Claude Code can already access, adding an MCP server would introduce deployment and security work without a clear benefit.
When MCP is the better fit
Use MCP when the AI application needs structured, current access to another system: querying a database, reading a managed knowledge source, operating a project tracker, calling a specialized calculator, or invoking an internal API. MCP servers describe available capabilities, and clients can discover tools, resources, and prompts before using them.
That connectivity has operational responsibilities. A production server needs appropriate authentication, authorization, input validation, logging, rate limits, secret handling, and lifecycle management. The MCP security guidance explicitly discusses risks such as confused-deputy attacks and token passthrough. Installing a server from an unknown source can expose more than a poorly written instruction file, because the server may handle credentials and perform actions against external systems.
Can Claude Skills and MCP work together?
Yes. A Skill can describe how and when to use tools exposed by an MCP server. Consider a customer-incident workflow:
- MCP servers expose read-only error tracking, deployment, and issue-tracker tools.
- A Skill defines the investigation order, evidence requirements, severity rules, and stopping conditions.
- Claude follows the Skill while calling only the connected tools allowed for the session.
- The final report distinguishes observed evidence from inference and asks for approval before any write action.
The MCP layer supplies live capabilities; the Skill supplies team-specific operational judgment. This combination is often more maintainable than embedding a long procedure in every prompt or creating one oversized MCP tool that hides the decision process.
Setup and portability tradeoffs
A basic Skill can be a single Markdown file, making it easy to inspect and version. More advanced skills may include scripts and host-specific frontmatter, which reduces portability. The Agent Skills specification defines the shared core, while Claude Code documents its own extensions.
An MCP integration has more moving parts: a server implementation, a supported transport, declared primitives, client configuration, and possibly OAuth or another authorization mechanism. In return, the interface is explicit and can serve multiple compatible AI applications. Portability still depends on each client's supported protocol version, primitives, and deployment environment.
Security review differs
For a Skill, review all instructions, referenced files, executable scripts, dynamic shell context, and tool approvals. Ask whether the skill can trigger automatically and whether its scope is broader than its job. Do not store credentials in the package.
For MCP, review the server publisher and code, requested data access, tool schemas, transport, credential storage, redirect and consent behavior, token audience validation, and write permissions. Prefer least privilege and explicit user confirmation for consequential operations. A Skill that invokes MCP tools inherits both sets of concerns.
PiSkill links to the original MCP Builder skill for implementation guidance and to Skill Creator for skill evaluation. These directory pages identify their sources; they are not substitutes for reviewing the original files and current official specifications.
Which should you use?
Use a Skill when the problem is mainly “Claude should follow this repeatable method.” Keep the instructions focused, test discovery, and version the workflow.
Use MCP when the problem is mainly “the AI application needs structured access to this external tool or current data source.” Design the connection and authorization as production software.
Use both when a reliable procedure must operate through live connected systems. Keep responsibilities separate: MCP exposes narrowly scoped capabilities, while the Skill explains the safe sequence, evidence standards, and decision boundaries.
For the underlying package format, read what Claude Code Skills are. To build one, continue with how to create a Claude Skill.