@orkestrel/mcp

A typed Model Context Protocol client/server for the @orkestrel line, bridging the @orkestrel/tool registry to MCP with pluggable HTTP, WebSocket, and stdio transports. createMCPServer exposes a live ToolManagerInterface; createMCPClient drives a remote MCP server and surfaces its tools as local ToolInterfaces. No agent runtime is required. The dispatch core is transport- and provider-agnostic (src/core — JSON-RPC 2.0, no HTTP, no as); every transport (Streamable HTTP over @orkestrel/router / @orkestrel/server, WebSocket over @orkestrel/websocket, and stdio over node:child_process) lives one layer out (src/server), each mechanism, not policy. Part of the @orkestrel line.

Install

npm install @orkestrel/mcp

Requirements

• Node.js >= 24
• ESM and CommonJS builds ship for both the core and server entry points
• @orkestrel/server and @orkestrel/router are peer dependencies (the HTTP spine the ./server transports mount onto)

Usage

Expose a tool registry over MCP, mounted on the HTTP spine:

import { createMCPServer } from '@orkestrel/mcp'
import { createMCPRoutes } from '@orkestrel/mcp/server'
import { createTool, createToolManager } from '@orkestrel/tool'

const tools = createToolManager()
tools.add(createTool({ name: 'add', execute: (a) => Number(a.x) + Number(a.y) }))

const mcp = createMCPServer({ name: 'calculator', version: '1.0.0', tools })
const routes = createMCPRoutes(mcp) // POST /mcp dispatches JSON-RPC (JSON or SSE per Accept)
router.add(routes)

Drive a remote MCP server as a client, over the same transport-agnostic core:

import { createMCPClient } from '@orkestrel/mcp'
import { createHTTPClientTransport } from '@orkestrel/mcp/server'

const client = createMCPClient({
	transport: createHTTPClientTransport({ url: 'http://localhost:3000/mcp' }),
})
await client.connect()
const tools = await client.tools()
const value = await client.call('add', { x: 2, y: 5 })

The SAME MCPClient drives a createWebSocketClientTransport or createStdioClientTransport instead — only the injected transport changes.

Guide

For the full surface — the JSON-RPC dispatch core, the three server transports (HTTP, WebSocket, stdio), the native session middleware, and usage patterns — see guides/src/mcp.md.

Package

Published with two entry points per the exports field in package.json: the environment-agnostic core (.) and the Node-only server surface (./server).

License

MIT © Orkestrel — see LICENSE.