@executor-js/plugin-mcp

Register Model Context Protocol servers as tool integrations for an executor. Supports both stdio-launched servers and remote (HTTP) servers, with optional OAuth.

Install

bun add @executor-js/sdk @executor-js/plugin-mcp
# or
npm install @executor-js/sdk @executor-js/plugin-mcp

Usage

import { createExecutor } from "@executor-js/sdk";
import { mcpPlugin } from "@executor-js/plugin-mcp";

const executor = await createExecutor({
  onElicitation: "accept-all",
  // Stdio integrations spawn a local subprocess — only enable for trusted
  // single-user contexts. See "Stdio environment" below for what they receive.
  plugins: [mcpPlugin({ dangerouslyAllowStdioMCP: true })] as const,
});

const scope = executor.scopes[0]!.id;

// Remote MCP server
await executor.mcp.addIntegration({
  scope,
  transport: "remote",
  name: "Context7",
  endpoint: "https://mcp.context7.com/mcp",
});

// Stdio MCP server (requires `dangerouslyAllowStdioMCP: true` above)
await executor.mcp.addIntegration({
  scope,
  transport: "stdio",
  name: "My Server",
  command: "npx",
  args: ["-y", "@my/mcp-server"],
});

// Every MCP tool is now part of the unified catalog
const tools = await executor.tools.list();

const result = await executor.tools.invoke("context7.searchLibraries", {
  query: "effect-ts",
});

Stdio environment

A stdio server does not inherit process.env. It receives the MCP SDK's safe-list (HOME, LOGNAME, PATH, SHELL, TERM, USER; the Windows equivalents on Windows), plus a short allowlist of proxy and CA variables — HTTP_PROXY, HTTPS_PROXY, NO_PROXY, their lowercase spellings, NODE_EXTRA_CA_CERTS, SSL_CERT_FILE, and SSL_CERT_DIR — so a server behind a corporate proxy can still reach the network. Nothing else travels, so a secret in the host environment stays there. Give the server anything more, an API key above all, through the integration's own env, which wins on a key collision. On Windows that collision is resolved case-insensitively, because the OS treats Path and PATH as one variable.

Using with Effect

If you're building on @executor-js/sdk/core (the raw Effect entry), import this plugin from its /core subpath instead — it returns the Effect-shaped plugin with Effect.Effect<...>-returning methods rather than promisified wrappers:

import { mcpPlugin } from "@executor-js/plugin-mcp/core";

Status

Pre-1.0. APIs may still change between beta releases. Part of the executor monorepo.

License

MIT