MCP server

McpServer exposes the 14 agent tools over the Model Context Protocol, so any MCP-compatible client (Claude Desktop, agent platforms, your own MCP client) can read, comment, and redline a DOCX without knowing anything about this library.

import { McpServer } from '@eigenpal/docx-editor-agents/mcp';
import { DocxReviewer, createReviewerBridge } from '@eigenpal/docx-editor-agents';

const reviewer = await DocxReviewer.fromBuffer(buffer, 'MCP Reviewer');
const server = new McpServer(createReviewerBridge(reviewer), {
  name: 'acme-docx-review',
  version: '1.0.0',
});

The server wraps any EditorBridge. In practice that is a reviewer bridge (file-backed, server-side); the same class would accept a live-editor bridge since the interface is identical.

Transport-agnostic handle()

The core is one synchronous method:

handle(message: JsonRpcMessage): JsonRpcResponse | null

• Accepts one JSON-RPC message; returns the response to send back, or null for notifications (which never get a reply).
• Never throws. Protocol-level problems come back as JSON-RPC errors; tool failures come back as successful responses with isError: true in the MCP content payload, per MCP convention.
• Implements initialize, tools/list, tools/call, and ping. Protocol version: 2025-06-18 (overridable via options).

tools/list advertises all 14 built-in tools with their JSON-Schema inputs. tools/call dispatches through the same executeToolCall the other integration shapes use. Note the headless caveats: against a reviewer bridge, read_selection and the page tools fail with descriptive errors, since there is no user and no rendered pages.

Because handle() is sync and transport-free, you can put it behind anything: HTTP, SSE, WebSocket, a queue consumer.

Hosting over HTTP

The host owns everything around the protocol: authentication, loading the right document for the caller, and persisting the result. The server only translates JSON-RPC into bridge calls.

import express from 'express';
import { McpServer } from '@eigenpal/docx-editor-agents/mcp';
import { DocxReviewer, createReviewerBridge } from '@eigenpal/docx-editor-agents';

const app = express();
app.use(express.json());

app.post('/mcp/:docId', requireAuth, async (req, res) => {
  // You own storage: load the caller's document...
  const buffer = await loadDocxForUser(req.user, req.params.docId);
  const reviewer = await DocxReviewer.fromBuffer(buffer, req.user.name);
  const server = new McpServer(createReviewerBridge(reviewer), {
    name: 'acme-docx-review',
    version: '1.0.0',
  });

  const reply = server.handle(req.body); // sync, never throws
  if (reply) res.json(reply);
  else res.status(204).end(); // notification: no reply by spec

  // ...and you own persistence: flush mutations back to storage.
  await saveDocxForUser(req.user, req.params.docId, await reviewer.toBuffer());
});

For high-traffic hosts, keep a reviewer per session instead of re-parsing per request; the server and bridge are plain objects with no global state.

Stdio transport

For local, single-document use there is a ready-made stdio loop (newline-delimited JSON-RPC on stdin/stdout):

import { readFile } from 'node:fs/promises';
import { runStdioServer } from '@eigenpal/docx-editor-agents/mcp';
import { DocxReviewer, createReviewerBridge } from '@eigenpal/docx-editor-agents';

const buffer = await readFile(process.argv[2]);
const reviewer = await DocxReviewer.fromBuffer(buffer, 'MCP Reviewer');

runStdioServer(createReviewerBridge(reviewer), { name: 'docx-review', version: '1.0.0' });

runStdioServer returns a handle with the underlying server, a feed() method (used by tests), and close(). It defaults to process.stdin / process.stdout but accepts any duck-typed streams, caps the frame buffer at 1 MiB, and answers malformed frames with JSON-RPC parse errors instead of crashing.

When to use MCP

Pick MCP when the agent side already exists and speaks MCP: a desktop assistant, an agent platform, an internal orchestrator. You get tool discovery and invocation for free, and the client needs zero knowledge of this library.

Pick the other shapes when you control both ends:

• Building a product UI: the live editor bridge gives you streaming, in-document feedback that MCP cannot.
• Building a server pipeline you also own: calling DocxReviewer directly is less moving parts than JSON-RPC framing.

Next steps

• DocxReviewer reference, the bridge these servers wrap
• Tools reference, what tools/list advertises
• AI redlining, the review semantics behind the tools
• API reference