# MCP vs skills: do you need a connection or a playbook?

A grounded distinction between MCP servers, tools, resources, prompts, and skills for teams extending AI agents.

MCP gives an AI application a standard way to reach external systems. Skills, in Eve/Cursor/Claude-style runtimes, give an agent a reusable playbook for a task. They often work together, but they are not substitutes. The clean design is usually MCP for access, skills for judgment.

## The common confusion

Both MCP and skills show up when people ask how to give an agent more context. That phrase hides two different needs. Sometimes the agent needs access to a system: list tables, read a file, search docs, create an issue. Sometimes the agent needs a method: review a migration, write in a brand voice, or triage an incident.

MCP is strongest for the first need. Skills are strongest for the second.

The confusion is understandable because both change what the model can do. But they change different things. MCP changes what systems the agent can reach. Skills change how the agent uses that access. Mixing them up leads to strange designs, like hiding API credentials inside a markdown playbook or turning a review rubric into a fake tool.

## MCP is an interface to capabilities

An MCP server exposes tools, resources, and prompts through a standard protocol. The client can discover what is available and call into those capabilities without each agent inventing a custom integration.

This is useful when the capability should be shared across many clients or agents. A Postgres MCP server, a Linear MCP server, or a docs search MCP server can serve multiple workflows.

MCP is especially useful when the external system is not owned by the agent author. A team can maintain one approved server for a database, CRM, or ticketing system, then let multiple agents use the same capability under the same access rules.

## Skills are playbooks

A skill is a playbook. It tells the agent how to perform a class of work: what to check, what to avoid, what output shape to use, what examples matter.

Skills should not hide credentials or grant authority. They can tell the model to use a read-only SQL tool carefully, but the read-only boundary must still live in the tool, database role, MCP server, or runtime policy.

A good skill makes the agent more consistent without giving it new powers. It might teach severity levels for code review, rules for customer-facing email, or the right way to answer analytics questions. The skill improves judgment; it does not replace permissions.

## Use both when capability needs a method

Many useful workflows need both layers. A data analyst needs database access and metric definitions. A support agent needs ticket access and escalation policy. A code reviewer needs GitHub access and review calibration.

In those cases, the design question becomes: what does the agent need to reach, and what does it need to know? MCP answers the first question. Skills answer the second.

## Decision table

| Choice | Use when | Avoid when |
| --- | --- | --- |
| MCP | The agent needs live access to external tools, resources, or server-provided prompts. | The agent only needs local procedure or writing rules. |
| Skill | The agent needs repeatable judgment, checklists, examples, or output standards. | The agent needs credentials or live system access. |
| Both | A workflow needs external capability plus domain-specific procedure. | The combination adds indirection without improving reuse or safety. |

## Examples

### Eve example

A database analyst can use MCP for database access and a skill for metric definitions, SQL safety rules, and answer format.

### Outside Eve

A coding assistant can connect to an MCP server while loading project-specific skills from the repository.

## FAQ

### Can a skill call an MCP tool?

A skill can tell the agent when and how to use the tool. The runtime still performs the actual tool call.

### Can MCP replace skills?

No. MCP can expose prompts, but skills remain useful for local, portable procedure and examples.

### Which is safer?

Neither by default. Safety comes from scopes, validation, approvals, and logs.

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- Published: 2026-07-01
- Updated: 2026-07-01
- Web page: https://www.evex.sh/learn/mcp-vs-skills
- This document: https://www.evex.sh/learn/mcp-vs-skills.md
- All guides: https://www.evex.sh/learn