MCP Server Patterns

# MCP Server Patterns

The Model Context Protocol (MCP) lets AI assistants call tools, read resources, and use prompts from your server. Use this skill when building or maintaining MCP servers. The SDK API evolves; check Context7 (query-docs for "MCP") or the official MCP documentation for current method names and signatures.

## When to Use

Use when: implementing a new MCP server, adding tools or resources, choosing stdio vs HTTP, upgrading the SDK, or debugging MCP registration and transport issues.

## How It Works

### Core concepts

- **Tools**: Actions the model can invoke (e.g. search, run a command). Register with `registerTool()` or `tool()` depending on SDK version.
- **Resources**: Read-only data the model can fetch (e.g. file contents, API responses). Register with `registerResource()` or `resource()`. Handlers typically receive a `uri` argument.
- **Prompts**: Reusable, parameterised prompt templates the client can surface (e.g. in Claude Desktop). Register with `registerPrompt()` or equivalent.
- **Transport**: stdio for local clients (e.g. Claude Desktop); Streamable HTTP is preferred for remote (Cursor, cloud). Legacy HTTP/SSE is for backward compatibility.

The Node/TypeScript SDK may expose `tool()` / `resource()` or `registerTool()` / `registerResource()`; the official SDK has changed over time. Always verify against the current [MCP docs](https://modelcontextprotocol.io) or Context7.

### Connecting with stdio