agboss/mcp works both ways:

• Using MCP servers — @McpServer declares a server and the server tools the workflow uses, @McpTool is a tool with that server injected. See Components → MCP and Tools.
• Exposing a workflow over MCP — @McpExpose lists the workflow's tools and workflow starts to offer to MCP clients (Claude Desktop, other agents); createMcpService serves them over stdio or HTTP. This page is about this side.

// src/mcp/job-scout.expose.ts
import { McpExpose } from "agboss/mcp";

@McpExpose({
  name: "job-scout-mcp",
  version: "1.0.0",
  exports: [SearchIssues, ChatWorkflowStart], // tools of the workflow, and its workflow starts
})
export class JobScoutMcp {}

• A @Tool / @McpTool export runs through the same adapter as an agent's tool call: its input and output DTOs become the JSON Schemas, both are validated, its timeout applies, it gets a callId. It must be a tool of the workflow (one of its agents' tools), else createMcpService fails naming it.
• A @WorkflowStart export becomes a tool that runs the workflow (app.execute); with any start exported, resume_workflow (app.resume) is offered too.

For Claude Desktop and other local clients, the service talks over stdin/stdout:

import { createMcpService } from "agboss/mcp";

const app = await createApp(JobScout);
const service = createMcpService(app, JobScoutMcp);
await service.connectStdio(); // serves until stdin closes

McpService knows no HTTP framework: handleSse(res, messageEndpoint, context) opens a session's event stream, handleMessage(req, res, sessionId, body) takes the client's messages. The context given to a session is what its tool calls see as ctx.executionContext — authorization stays out of the tools' code (Context and Authorization).

import { createServer } from "node:http";

createServer((req, res) => {
  const url = new URL(req.url ?? "/", "http://localhost");
  if (req.method === "GET" && url.pathname === "/mcp") {
    const context = { tenant: req.headers.authorization }; // bound to this session
    void service.handleSse(res, "/mcp/messages", context);
    return;
  }
  if (req.method === "POST" && url.pathname === "/mcp/messages") {
    void service.handleMessage(req, res, url.searchParams.get("sessionId") ?? "");
    return;
  }
  res.writeHead(404).end();
}).listen(3001);

service.connect(transport, context) takes any MCP SDK transport instead (e.g. in tests, an in-memory pair).