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Field guide 028 min read

Agent Pluginsvs Skillsvs MCP.

A Plugin is the portable package. A Skill teaches the agent how to work. MCP connects the agent to tools and live context.

Updated 07 Aug 2026Based on Agent Plugins v1.0.0
Agent Plugin / portable packageplugin.json
Optional component 01

Skills

Reusable instructions, workflows, examples, and supporting files that teach an agent how to approach a task.

skills/name/SKILL.md
Optional component 02

MCP servers

Standard connections that let an agent discover tools, read resources, and use prompts supplied by external systems.

mcp.json
One package boundaryEither component, both, or neither

Quick answer

Agent Plugins,
Skills, and MCP.

They solve different parts of the same problem: how to package an agent capability, explain its workflow, and connect it to external systems.

01
Agent Plugins
Agent Plugins define the distribution boundary. Under v1.0.0, the root plugin.json manifest identifies a portable package. The package can include Skills, MCP server configuration, both, or neither. Package conformance does not by itself guarantee security, client compatibility, or quality.
02
Skills
Skills define the instruction boundary. A SKILL.md file describes when a capability applies and how an agent should perform the work. Supporting scripts, references, and assets can make the workflow repeatable without requiring a live external service.
03
MCP
MCP defines the connection boundary. An MCP server exposes tools, resources, and prompts through a standard protocol so an agent can query current data or perform actions. The client remains responsible for connection setup, permissions, and runtime controls.

Comparison / 01

Agent Plugins,
Skills, and MCP compared.

The terms are often grouped together because they cooperate, not because they are interchangeable.

Primary job

Agent Plugin
Distribute a portable package
Skill
Teach a repeatable way of working
MCP
Connect to tools and live context

Defining artifact

Agent Plugin
Root plugin.json manifest
Skill
SKILL.md plus optional support files
MCP
Server implementation and protocol endpoint

Inside a plugin

Agent Plugin
The package root
Skill
skills/<name>/SKILL.md
MCP
Root mcp.json connection config

Gives the agent

Agent Plugin
A portable unit to discover and load
Skill
Instructions, judgment, and workflow
MCP
Tools, resources, and prompts

Can stand alone?

Agent Plugin
Yes — even a manifest-only package is valid
Skill
Yes — skills can be distributed independently
MCP
Yes — servers can be connected directly

Best fit

Agent Plugin
A multi-part capability intended for portable distribution
Skill
A repeatable process or domain-specific method
MCP
Live data, external actions, or system integration

Does not guarantee

Agent Plugin
Security, quality, or universal client compatibility
Skill
External connectivity or successful execution
MCP
A complete workflow or conforming plugin package

Anatomy / 02

How Agent Plugins package Skills and MCP.

A useful mental model: package the capability, teach the workflow, connect the live systems.

Layer 01

The package layer

Agent Plugin

A self-contained directory with a required plugin.json manifest and optional standardized components. It gives clients one portable unit to discover, validate, install, and load.

  • Required: plugin.json with $schema and name
  • Optional: Skills under skills/
  • Optional: MCP server configuration in mcp.json
Layer 02

The instruction layer

Agent Skill

A folder centered on SKILL.md. It packages task-specific knowledge: when to use the skill, how to execute the work, and which scripts, references, or assets support it.

  • Required: YAML frontmatter plus Markdown instructions
  • Optional: scripts/, references/, and assets/
  • Best for repeatable processes and domain judgment
Layer 03

The connection layer

MCP

An open protocol for connecting AI applications to external systems. MCP servers can expose executable tools, contextual resources, and reusable prompts through a standard interface.

  • Tools perform actions or retrieve information
  • Resources supply contextual data
  • Prompts provide reusable interaction templates

Decision guide / 03

When to use a Plugin,
Skill, or MCP server.

The common combination

A Skill explains the workflow. MCP provides the live capabilities. The Plugin carries them together.

01

Need the agent to follow a repeatable process?

Start with a Skill.

Write the workflow, checks, examples, and references in SKILL.md.

02

Need current data or an action in another system?

Use MCP.

Connect a server that exposes the required tools, resources, or prompts.

03

Need to ship the capability as one portable unit?

Wrap it as an Agent Plugin.

Add plugin.json, then include only the components the capability needs.

In practice / 04

One folder makes the boundary visible.

Clients discover standardized components from fixed locations. The manifest does not have to inline every component configuration.

View the official reference example
example-plugin/AP v1.0.0
example-plugin/
├── plugin.json # required manifest
├── skills/
│ └── research/
│ ├── SKILL.md
│ ├── scripts/
│ └── references/
├── mcp.json # optional MCP config
├── README.md
└── LICENSE
plugin.json is the only required file in the smallest valid package.

Corrections / 05

Four shortcuts that cause confusion.

01

“Agent Plugin” is another name for a Skill.

No. A Skill is one component type an Agent Plugin can contain.

02

Every Agent Plugin must include Skills and MCP.

No. Both component locations are optional; a package may include either, both, or neither.

03

MCP tells the agent how to complete the whole task.

Not necessarily. MCP standardizes connections; a Skill can hold the higher-level workflow and judgment.

04

The Agent Plugins standard is a plugin store.

No. Version 1.0 defines a portable package format, not a marketplace or recommendation system.