The simple version
An MCP tool describes one action: find an invoice, update a ticket, or create a draft. A skill describes how to complete a larger job: which actions to use, in what order, what to check, and when to ask a person for approval.
Think of a tool as a button and a skill as the operating procedure. The procedure does not replace the button or your product’s rules. It helps the agent use the available buttons consistently.
Customer goal
Skill: the playbook
MCP tools: the actions
Tools, prompts, and skills do different jobs
| Plain meaning | Example | |
|---|---|---|
| Tool | A structured action an agent can request from connected software. | find-order or prepare-refund |
| Prompt | A reusable starting message, usually selected by a person. | “Summarize this customer account.” |
| Skill | Instructions and supporting material an agent loads when a task calls for a particular workflow. | Investigate a refund, check policy, prepare the change, and request approval. |
A skill can coordinate several tools, include decision rules and examples, and point to supporting references. It may also describe tools from more than one service. The tools still perform the work; the skill supplies know-how.
What a skill contains
The open Agent Skills format represents a skill as a folder. Its required SKILL.md file contains a name, a description of when the skill applies, and instructions for the agent. Optional folders can hold references, examples, templates, assets, and scripts.
- 1
Discover
The agent sees a short name and description, without loading every instruction into every conversation.
- 2
Load
When the task matches, it reads the full playbook and only the supporting files it needs.
- 3
Work
It follows the guidance, calls available tools, checks results, and pauses for required decisions.
Where MCP enters the picture
There are two useful connections between MCP and skills:
- Skills for building MCP products are available now. The MCP project publishes development skills that guide coding agents through server design, authentication, deployment, MCP Apps, and packaging. These are installed in a supported coding agent; they are not a new server capability.
- Delivering skills through MCP is experimental. The Skills over MCP Working Group is exploring how a connected server could let a host discover and read skills at runtime. That could keep a product’s tools and its operating guidance together, but the proposal is still incubating and is not part of the stable MCP specification.
Why product teams should care
More reliable workflows
The agent gets the sequence, decision points, and checks that do not fit cleanly in individual tool descriptions.
Less context clutter
A host can expose short descriptions first and load detailed guidance only when it is relevant.
Guidance that evolves
If runtime delivery becomes standard, a server could update its playbook as the product and tools change, without a separate skill installation.
Shared product knowledge
The same approved procedure can help different compatible agents carry out a task consistently.
Skills do not create authority
A skill is untrusted input that can influence an agent. It should never override the user, product permissions, or organizational policy. Instructions arriving from a server also should not silently run local scripts or gain access to other connected services.
- Show where each skill came from and let people inspect it.
- Keep identity, authorization, validation, rate limits, and audit logs in the tools and product APIs.
- Require clear approval for consequential actions and any local code execution.
- Limit a skill to the data and tools needed for its stated job.
- Version and test the playbook alongside the tools it describes.
Experimental as of August 2026
Design the playbook now. Keep the delivery mechanism flexible.
Teams can already write and test Agent Skills, and use official skills to help build MCP servers. For serving skills through MCP, follow the working group rather than depending on today’s draft methods or URI conventions in production.
Sources and further reading: the MCP project’s Build with Agent Skills guide, the Skills over MCP Working Group repository, its experimental skills extension draft, and the Agent Skills specification.
Where to start
Choose one important workflow that takes several tools and real judgment.
Write down its sequence, exceptions, permissions, approvals, and success checks. That is the beginning of a useful skill—and a sharper MCP tool design.
Design your MCP workflow with Strata →