What is an MCP server?
An MCP server is a program that exposes tools, data, and prompts to AI assistants through the Model Context Protocol (MCP) — the open standard that lets agents like Claude, Cursor, and Claude Code use external capabilities. In short: it's how you give an AI the ability to do things — query a database, browse a site, open a pull request — instead of only talking about them.
The Model Context Protocol is an open standard introduced by Anthropic in late 2024 for connecting AI applications to external systems. Before MCP, every assistant needed a custom integration for every tool. MCP replaces that with one shared interface — often described as a “USB-C port for AI”: build a server once, and any MCP-compatible client can use it.
An MCP server can offer three kinds of things to a connected AI:
- Tools — functions the model can call, each with a typed input schema (for example
search_issuesorrun_query). Tools are the reason most people add a server; they range from read-only lookups to actions that write data or have real-world side effects. - Resources — data the server makes available to read, like files, records, or documents.
- Prompts — reusable prompt templates the server publishes for common tasks.
MCP uses a client–server model over JSON-RPC. The AI application runs an MCP client; each capability provider is an MCP server. On connect, the client performs a handshake (initialize), then asks the server what it offers (tools/list), and from then on can call those tools on the model's behalf. A single client can hold many server connections at once.
There are two common transports:
- stdio — the server runs locally as a subprocess (started by a command like
npxoruvx). Best for local tools and files. - Streamable HTTP / SSE — the server is remote, reached over a URL. Best for hosted, multi-user services.
A server can expose tools that write data or take actions, so trust matters. Before adding one, it's worth checking who publishes it, whether its tools are read-only or destructive, whether it needs credentials, and whether it's actively maintained. This is exactly what MCPExplorer verifies: we run a live handshake to extract each server's real tools, label every tool's risk level, and compute a trust score from provenance, verification, adoption, and freshness.
A few well-known, verified servers from the index — each page shows its tools, install command, and trust breakdown:
What is an MCP server in simple terms?
It's a small program that gives an AI assistant a set of abilities — like reading a database, searching the web, or editing files — through a shared standard called the Model Context Protocol. The AI connects to the server and can then call the tools the server offers.
Who created the Model Context Protocol?
Anthropic introduced MCP as an open standard in late 2024, and released it with open-source SDKs and reference servers. It is now supported by many AI clients beyond Claude, including editors and agent frameworks.
What's the difference between an MCP client and an MCP server?
The client lives inside the AI application (for example Claude Desktop, Cursor, or Claude Code) and initiates connections. The server is the separate program that exposes tools, resources, and prompts. One client can connect to many servers at once.
Do I need to write code to use an MCP server?
Usually no. Most MCP clients let you add a server by pasting an install command (like an npx or uvx command) or a remote URL into a config file or settings screen. Building your own server requires code, but using existing ones generally does not.
Are MCP servers safe to use?
It depends on the server. Because a server can expose tools that write data or take real-world actions, you should check who publishes it, whether its tools are read-only or destructive, and whether it needs credentials. MCPExplorer labels each server's tool risk and verification status to make that judgement easier.
Where can I find MCP servers?
MCPExplorer indexes MCP servers with their verified tools, install commands, transport, and a trust score. You can browse the full index, see a curated ranking of the best servers, or search by capability and risk level.
Browse 863 indexed MCP servers with 1,131 verified tools — or start with the best.