mcp-servers

name	mcp-servers
description	Building MCP servers with tools, resources, prompts, decorators, and HTTP/stdio transports in Rudder
license	MIT
appliesTo	["@rudderjs/mcp"]
trigger	building an MCP server, using `@McpServer` / `@Tool` decorators, exposing tools or resources, or choosing HTTP vs stdio transport
skip	consuming an external MCP server from an Agent — use `mcpClientTools()` and load `ai-tools` instead
metadata	{"author":"rudderjs"}

MCP Servers

When to use this skill

Load when you're building a Model Context Protocol (MCP) server — exposing tools, resources, or prompts to AI coding assistants. If you're consuming an external MCP server inside an Agent, load ai-tools instead and use mcpClientTools().

Quick Reference

Task	Open
Tools — McpTool, schema, outputSchema, name derivation, McpResponse helpers	rules/tools.md
Resources + Prompts — McpResource with URI templates, McpPrompt with arguments	rules/resources-and-prompts.md
Assemble + register a server — McpServer base class, decorators, Mcp facade	rules/server-assembly.md
Transports — stdio (Mcp.local) vs HTTP/SSE (Mcp.web), middleware	rules/transports.md
Test + DI — McpTestClient, DI-injected tool classes	rules/testing-and-di.md

Key concepts (load once)

• McpServer — base class. Declares protected tools, resources, prompts arrays of classes.
• McpTool / McpResource / McpPrompt — base classes. Implement handle() + schema() (tools) / uri() (resources) / arguments() (prompts).
• Decorators — @Name, @Version, @Instructions, @Description write metadata via reflect-metadata.
• Name auto-derivation — WeatherTool → weather. PascalCase → kebab-case, minus Tool suffix.
• McpResponse — return helper: McpResponse.text(s), .json(obj), .error(msg). Errors thrown from handle() are auto-wrapped.
• DI integration — tool/resource/prompt classes resolve via the framework's container when available; falls back to new T().
• McpTestClient — in-memory client for testing servers without spinning up a transport.

Examples

See packages/mcp/src/index.test.ts for end-to-end tests and playground/app/Mcp/ for a working server (EchoMcpServer + secured variant).