What Is an MCP Server & How to Connect One (2026)

Short answer: An MCP server is a program that exposes tools, data, and workflows to any compatible AI client — Claude, ChatGPT, Cursor, VS Code, n8n, and more — using the Model Context Protocol standard. Once your server is running, any MCP-capable AI can discover and call its capabilities at runtime, without custom integrations per client.

This guide focuses specifically on the server side of MCP: what it is under the hood, how the two transport types work, what local and remote servers each look like in practice, which MCP servers are widely used in 2026, and how to connect one to Claude or ChatGPT. For a deeper look at the full MCP protocol — its history, governance, and client-side architecture — read our complete MCP guide.

If you run a WordPress site and want to use it as an MCP server without writing a line of code, that is exactly what Easy MCP AI does. We’ll cover it in detail below.

What Is an MCP Server?

An MCP server is any program that implements the server side of the Model Context Protocol — the open standard originally created at Anthropic and donated to the Linux Foundation’s Agentic AI Foundation on December 9, 2025.

The server’s job is to advertise its capabilities (via */list endpoints) and respond to requests (via */call or */read). The AI client — Claude Desktop, ChatGPT, Cursor, or any other MCP host — connects to the server at session start, discovers what it can do, and then invokes those capabilities on the user’s behalf throughout the conversation.

Crucially, a single MCP server works with every compliant client. You write the server once. Every client that speaks MCP can use it.

MCP Server Meaning in Plain Terms

If REST APIs are menus that humans order from by writing code, MCP servers are menus that AI models read, understand, and order from autonomously — with your approval before any consequential action. The server does not know or care which AI is calling it. The client does not know or care how the server is implemented. The protocol handles the handshake.

How an MCP Server Works: The Protocol Stack

MCP sits on two layers:

Data layer — JSON-RPC 2.0 messages that define lifecycle, primitives, and notifications
Transport layer — the channel over which those messages travel

JSON-RPC 2.0: The Message Format

Every message between an MCP client and server is a JSON-RPC 2.0 object. A tool call looks like this:

{
  "jsonrpc": "2.0",
  "id": 3,
  "method": "tools/call",
  "params": {
    "name": "wp_create_post",
    "arguments": {
      "title": "Hello World",
      "status": "draft"
    }
  }
}

The server responds with a content array. Both sides begin by exchanging initialize / initialized messages to negotiate protocol version and declare which capabilities each side supports — tools, resources, prompts, sampling, elicitation, and so on. Nothing happens until that handshake completes.

The Three Server Primitives

Every MCP server communicates through three primitive types:

Primitive	What it is	Who controls it	Example
Tools	Executable functions the AI can invoke	Model (AI decides when to call)	`wp_publish_post`, `query_database`, `send_email`
Resources	Read-only URI-addressable data	Application (host decides what to surface)	Site schema, file contents, API response cache
Prompts	Reusable interaction templates	User (invoked via slash command or menu)	“Audit SEO for this post”, “Summarise this week’s orders”

Tools are the most commonly implemented primitive. A minimal useful MCP server can expose only Tools and still cover most agentic workflows.

STDIO vs Streamable HTTP: The Two Transports

This is the most important architectural decision when building or choosing an MCP server. The two transports carry identical JSON-RPC 2.0 messages — only the channel differs.

	STDIO Transport	Streamable HTTP Transport
Where server runs	Locally, on the same machine as the client	Anywhere reachable over HTTPS
How it launches	Host spawns the server as a child process	Server runs independently; client connects via HTTP
Communication	Standard input/output streams	HTTP POST for requests; optional Server-Sent Events for streaming
Auth model	OS-level process isolation	OAuth 2.1, bearer tokens, API keys
Best for	Local dev tools, filesystem, code execution	Hosted services, SaaS integrations, multi-user servers
Example	`npx @modelcontextprotocol/server-filesystem`	Easy MCP AI, Sentry MCP server
Concurrent clients	Typically one (1:1 with host process)	Many (one server instance, many clients)

STDIO is simpler to build and debug — no network, no auth. Claude Desktop and Cursor both support it. You configure it via a JSON file pointing to the server’s executable.

Streamable HTTP is what production, multi-user, or remote deployments use. The client connects to a URL (https://yoursite.com/mcp) and the server handles authentication (usually OAuth 2.1) before accepting requests. This is the transport that lets a single WordPress install serve Claude, ChatGPT, and n8n simultaneously.

Local vs Remote MCP Servers

The local/remote distinction maps closely to, but is not identical to, the STDIO/HTTP distinction. A server is “local” if it runs on the same machine as the AI client. It is “remote” if it runs elsewhere and is accessed over the network.

Local MCP servers are great for:

Filesystem access (@modelcontextprotocol/server-filesystem)
Running shell commands
Reading local databases (SQLite, etc.)
IDE-level code tools (used by Cursor, VS Code)

Remote MCP servers are great for:

SaaS products (GitHub, Sentry, Notion, WordPress)
Multi-user scenarios where one server serves many clients
Services that should not require anything installed on the user’s machine
Persistent state that should outlive a single desktop session

For WordPress specifically, remote is the right choice. Your WordPress data lives on a server. The MCP server should live there too, not require a Node.js proxy on every user’s laptop.

Popular MCP Servers in 2026

The MCP ecosystem has grown quickly since the November 2024 release. The modelcontextprotocol/servers repository contains the official reference implementations; the broader community server directory now lives at the MCP Registry (registry.modelcontextprotocol.io). A few widely used examples:

Server	What it exposes	Transport
`@modelcontextprotocol/server-filesystem`	Read/write local files	STDIO
`@modelcontextprotocol/server-fetch`	Fetch & convert web content	STDIO
`@modelcontextprotocol/server-git`	Read/search/manipulate Git repos	STDIO
`@modelcontextprotocol/server-memory`	Knowledge-graph persistent memory	STDIO
Sentry MCP server	Errors, issues, traces	Streamable HTTP
Easy MCP AI (WordPress)	214 WordPress tools	Streamable HTTP

For WordPress specifically, there are three paths in 2026: Easy MCP AI (the most complete self-hosted option), the official WordPress MCP Adapter (pairs with the WordPress 6.9 Abilities API), and WordPress.com’s built-in MCP for hosted sites.

How to Connect an MCP Server to Claude

Claude Desktop and Claude.ai both support Streamable HTTP MCP connectors. Claude Code and Claude Desktop also support STDIO.

For a remote MCP server (Streamable HTTP) in Claude Desktop or Claude.ai:

Open Settings → Connectors (or Settings → MCP depending on your Claude version)
Click Add custom connector
Enter the server’s URL (e.g., https://yoursite.com/mcp)
Complete the OAuth flow if the server requires it
Start a new conversation — Claude will list available tools when you ask

For a local MCP server (STDIO) in Claude Desktop:

Edit your claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/):

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/Users/you/Documents"]
    }
  }
}

Restart Claude Desktop. The server starts automatically.

How to Connect an MCP Server to ChatGPT

ChatGPT added MCP client support in Developer Mode, announced in September 2025 via the OpenAI Developer Community. Developer Mode provides full MCP client support for all tools — both read and write. Setup guide: platform.openai.com/docs/guides/developer-mode.

In ChatGPT Developer Mode, you add a custom MCP connector by providing the server URL. The server must support Streamable HTTP transport and OAuth 2.1 or token-based auth. Once connected, ChatGPT can discover and call tools exactly as Claude does — the server sees no difference between clients.

Easy MCP AI supports both Claude and ChatGPT in parallel. One install, one OAuth flow per client.

How to Build an MCP Server

Building a basic MCP server is straightforward if you are comfortable with code. The MCP project maintains official SDKs for TypeScript, Python, C#, Go, Java, Rust, Swift, Ruby, PHP, and Kotlin.

A minimal Python MCP server that exposes one tool:

from mcp.server import Server
from mcp.server.stdio import stdio_server
from mcp import types

app = Server("my-server")

@app.list_tools()
async def list_tools() -> list[types.Tool]:
    return [
        types.Tool(
            name="get_time",
            description="Returns the current UTC time.",
            inputSchema={"type": "object", "properties": {}, "required": []},
        )
    ]

@app.call_tool()
async def call_tool(name: str, arguments: dict):
    from datetime import datetime, timezone
    if name == "get_time":
        return [types.TextContent(type="text", text=datetime.now(timezone.utc).isoformat())]

if __name__ == "__main__":
    import asyncio
    asyncio.run(stdio_server(app))

Run it, add it to your Claude Desktop config, and it works. For production remote servers, you swap stdio_server for an HTTP server (FastAPI, Flask, Express, etc.) and add OAuth 2.1 handling.

Testing your server: The MCP Inspector lets you test any server interactively without a full AI client:

npx @modelcontextprotocol/inspector

It sends initialize, tools/list, and tools/call requests and shows the raw JSON-RPC exchange — the fastest way to debug a server implementation.

MCP on WordPress: Easy MCP AI

For WordPress sites, the most complete MCP server available is Easy MCP AI — a free, open-source plugin that turns any WordPress install into a fully compliant remote MCP server.

It ships 214 tools across three tiers:

96 core WordPress tools — posts, pages, media, menus, users, taxonomy, comments, blocks, revisions, meta, themes, templates, custom post types, site settings
80 plugin tools — WooCommerce (46), BuddyPress (10), The Events Calendar (10), ACF (6), Yoast SEO (3), Rank Math (3), AIOSEO (2)
38 data integration tools — Google Analytics (11), SEMrush (13), Google Search Console (6), DataForSEO (8)

No Node.js, no proxy, no custom server code. Installation is:

Install the plugin from wordpress.org/plugins/easy-mcp-ai
Enable the relevant plugin integrations under Easy MCP AI → Plugins
Copy your MCP URL from Easy MCP AI → Dashboard
Add it as a custom connector in Claude, ChatGPT, Cursor, n8n, or any other MCP client
Complete the OAuth 2.1 one-click flow

Easy MCP AI connects to 16 AI clients: Claude.ai, Claude Desktop, Claude Code, Cursor, Cline, Gemini CLI, GitHub Copilot, Google Antigravity, LibreChat, Manus, n8n, Pydantic AI, Roo Code, Windsurf, Zed, and ChatGPT.

Security is handled at the server level: credentials encrypted with AES-256-GCM (HKDF-derived per-provider keys), OAuth 2.1 with per-tool and per-content-type permission scoping, WordPress capability checks, and rate limiting. Everything stays on your server. See the security details.

Example prompts that work the moment you connect:

“List my 10 most recent posts and flag any with titles over 60 characters.”
“Find all WooCommerce orders placed this week with status ‘processing’ and summarise the totals.”
“Pull this month’s top 5 organic queries from Search Console and suggest a follow-up post for each.”
“Update the Rank Math focus keyword on post ID 142 to ‘mcp server’ and regenerate the meta description.”

For the full plugin integration guides: WooCommerce · Yoast SEO · Rank Math · AIOSEO · Google Analytics · ACF

Key Facts

An MCP server is any program that exposes Tools, Resources, or Prompts to MCP-capable AI clients via the Model Context Protocol
The wire format is JSON-RPC 2.0; all communication is request/response or notification
Two official transports: STDIO (local subprocess, no network) and Streamable HTTP (remote, OAuth-secured)
Three server primitives: Tools (AI-controlled actions), Resources (app-controlled read data), Prompts (user-controlled templates)
A single MCP server works with every compliant client — Claude, ChatGPT, Cursor, VS Code, n8n, and more
Local servers run on the user’s machine (best for filesystem, IDE tools); remote servers run on a host and serve many clients simultaneously
ChatGPT MCP support launched in Developer Mode (September 2025); requires Streamable HTTP transport
Official SDKs exist for TypeScript, Python, C#, Go, Java, Rust, Swift, Ruby, PHP, and Kotlin
Easy MCP AI is a free WordPress plugin that turns any WordPress site into a remote MCP server with 214 tools, no code required

Conclusion

An MCP server is the supply side of the agentic AI stack — the program that gives AI models real capabilities to act in the world. Understanding what a server is, which transport to use, and how to connect it to Claude or ChatGPT is the foundational knowledge every team building AI-powered workflows in 2026 needs.

If you run WordPress and want to skip the build-it-yourself step, Easy MCP AI is the fastest path from zero to a production-grade remote MCP server with a full toolset for content, e-commerce, SEO, and analytics.

→ Get Easy MCP AI — free on WordPress.org

Official Sources

All external claims in this article were verified against the following primary sources:

MCP Architecture & Specification

Model Context Protocol — Architecture Overview (modelcontextprotocol.io) — verified source for JSON-RPC 2.0, STDIO/Streamable HTTP transports, primitives, lifecycle, and initialization exchange
MCP Specification (latest) (modelcontextprotocol.io)
MCP Reference Server Implementations (github.com/modelcontextprotocol)
MCP Inspector (github.com/modelcontextprotocol)

ChatGPT MCP Support

MCP server tools now in ChatGPT — developer mode (community.openai.com, September 2025) — confirmed full MCP client support in ChatGPT Developer Mode for all tools (read and write)
OpenAI Developer Mode guide (platform.openai.com)

MCP Governance

Anthropic — Donating the Model Context Protocol and establishing the Agentic AI Foundation (anthropic.com, December 9, 2025)

WordPress MCP

Easy MCP AI plugin (wordpress.org) — tool counts, AI client list, and security details verified in plugin codebase
WordPress MCP Adapter (github.com/WordPress)
Introducing the WordPress MCP Adapter (WordPress Developer Blog, February 4, 2026)