@modelcontextprotocol/ext-tasks

Call tools through generation-agnostic Tasks requester APIs. The package also provides 2025-11-25 Tasks receiver support for sampling and elicitation requests.

Install

npm install @modelcontextprotocol/ext-tasks

Use the client entry point when your application calls tools:

import {
  createTaskSessionFromClient,
  resultFromTaskOutcome,
} from "@modelcontextprotocol/ext-tasks/client";

Call a tool

Create a session from a connected MCP SDK Client. The same call handles immediate results and durable task-backed execution.

const session = createTaskSessionFromClient(client, {
  endpointId: "production-reports",
});

try {
  const execution = await session.callTool("generate_report", {
    format: "pdf",
  });
  const { outcome } = await execution.settle();
  const result = resultFromTaskOutcome(outcome);
} finally {
  await session.close();
}

Receive 2025-11-25 Tasks requests

Use the receiver entry point to handle 2025-11-25 task-backed sampling and elicitation requests.

import { bindTaskReceiver } from "@modelcontextprotocol/ext-tasks/receiver";

const receiver = bindTaskReceiver(client, {
  methods: { "sampling/createMessage": true },
  sampling: async (request, { signal }) =>
    runSampling(request.params, { signal }),
});

try {
  await serve();
} finally {
  receiver.close();
}

The binding owns task state, retention, cancellation, lifecycle handlers, and status notifications. Merge receiver.capabilities into the host's advertised Tasks capability.

Documentation

Start with the TypeScript package guide and getting-started walkthrough. Then choose the task you need:

• Migrate an existing MCP SDK client
• Execute and control tools
• Handle application input and recover tasks
• Bind a 2025-11-25 Tasks receiver
• Integrate custom adapters or schemas
• Troubleshoot setup and lifecycle failures

For normative wire behavior, use the MCP Tasks specification.

Public entry points

• @modelcontextprotocol/ext-tasks/client — requester sessions, execution, input routing, recovery, and SDK adapters
• @modelcontextprotocol/ext-tasks/receiver — 2025-11-25 Tasks receiver binding
• @modelcontextprotocol/ext-tasks/core — generation-neutral JSON, codecs, errors, and identifiers
• @modelcontextprotocol/ext-tasks/core/v1 — generated 2025-11-25 Tasks schemas and wire types
• @modelcontextprotocol/ext-tasks/core/v2 — generated Tasks V2 schemas and wire types

Source is emitted as ESM JavaScript, TypeScript declarations, and source maps in dist.