What Is an MCP Server? A Practical Guide for Teams Using AI Tools

By Kent Fenwick, Runner co-founder — 2026-03-17

If you have spent any time around AI tools lately, you have probably heard people say MCP as if everyone should already know what it means. Most people do not, and that is fine. A lot of the conversation moves too fast and assumes the acronym is the explanation.

The shortest explanation I can give you

MCP stands for Model Context Protocol. It is an open standard for connecting AI applications to external systems. I think of an MCP server as a standard port that lets an AI client discover tools, read resources, and use structured prompts without every vendor inventing a custom integration layer from scratch.

• The server exposes capabilities in a standard shape.
• The client connects and discovers what the server can do.
• The host AI application can then use those capabilities inside a workflow.
• The connection becomes more predictable than one-off custom glue code.

The three participants that matter

• MCP host: the AI application coordinating the experience.
• MCP client: the connection layer the host uses for each server.
• MCP server: the program exposing context, tools, or prompts to the client.

That host-client-server split matters more than people think. It is part of what makes MCP useful beyond a single vendor demo. The host can connect to multiple servers. Each server can expose a different part of the world.

What an MCP server can actually expose

• Tools: executable functions the AI application can call.
• Resources: structured context such as file contents, database records, or API responses.
• Prompts: reusable prompt templates or interaction scaffolding.

Why teams care

The old way does not scale very well. Every new AI product wants its own connector model, its own auth flow, its own assumptions about schemas, and its own maintenance burden. MCP matters because it gives teams a more reusable way to expose systems to AI applications.

• Less repetitive integration work.
• A cleaner path for internal systems to become usable in AI workflows.
• Less vendor lock-in around how tools connect to AI applications.
• A more standard mental model for permissions, discovery, and execution.

Local and remote MCP servers

This is one of the practical details worth understanding. MCP supports local servers and remote servers, and the difference changes how you think about performance, auth, and trust.

• Local servers usually communicate over stdio and run on the same machine as the client or host.
• Remote servers usually communicate over HTTP and can serve many clients.
• Local is often simpler for private developer workflows.
• Remote is often better when you want shared infrastructure, standard auth, or team access.

What happens when a client connects

Under the hood, MCP is not magic. It is a stateful protocol built on JSON-RPC. The client and server initialize, negotiate capabilities, and then the client can discover primitives like tools or resources before using them.

• Initialize: client and server negotiate protocol version and capabilities.
• Discover: the client lists the tools, resources, or prompts the server exposes.
• Use: the client reads a resource or calls a tool when the host needs it.
• Update: the server can notify the client if available tools or capabilities change.

What MCP does not solve

This is the part people often miss. MCP is about context exchange. It does not decide how good your prompts are, how your agent should reason, or whether your product actually deserves to exist. It gives you a standard way to connect systems. You still need to build the experience.

Where teams go wrong

• They think MCP alone turns a bad workflow into a good one.
• They expose too much without thinking through permissions and trust boundaries.
• They treat every internal system like it needs an MCP server immediately.
• They forget that a clean tool surface matters just as much as having a standard.

Should your team build one

If your company has useful internal systems and you want multiple AI clients or agents to access them in a consistent way, I think the answer is increasingly yes. If you only have one narrow use case and one controlled integration, maybe not yet. Standards matter most once reuse starts to matter.

This is why I am bullish on MCP. Standards win when they make the boring parts easier. MCP makes the boring part of AI integration more legible, more reusable, and a little less fragile. That is a bigger deal than it sounds.