[SEP-2663] refactor!: remove 2025-11 experimental tasks (modelcontextprotocol#2128)

Author: felixweinberger

.changeset/fix-failed-task-result-retrieval.md

@@ -0,0 +1,6 @@
+---
+'@modelcontextprotocol/core': major
+'@modelcontextprotocol/server': major
+'@modelcontextprotocol/client': major
+---
+SEP-2663: remove 2025-11 experimental tasks (TaskManager, experimental.tasks.* accessors). Tasks are now Extensions Track.

.changeset/sep-2663-tasks-removal.md

@@ -104,9 +104,7 @@ The repo also ships “middleware” packages under `packages/middleware/` (e.g.
 
 ### Experimental Features
 
-Located in `packages/*/src/experimental/`:
-
-- **Tasks**: Long-running task support with polling/resumption (`packages/core/src/experimental/tasks/`)
+Located in `packages/*/src/experimental/`. Currently empty.
 
 ### Zod Schemas
 
@@ -201,7 +199,6 @@ The `ctx` parameter in handlers provides a structured context:
   - `notify(notification)`: Send related notification back
 - `http?`: HTTP transport info (undefined for stdio)
   - `authInfo?`: Validated auth token info
-- `task?`: Task context (`{ id?, store, requestedTtl? }`) when task storage is configured
 
 **`ServerContext`** extends `BaseContext.mcpReq` and `BaseContext.http?` via type intersection:
 

CLAUDE.md

@@ -544,7 +544,7 @@ All requests have a 60-second default timeout. Pass a custom `timeout` in the op
 ```ts source="../examples/client/src/clientGuide.examples.ts#errorHandling_timeout"
 try {
     const result = await client.callTool(
-        { name: 'slow-task', arguments: {} },
+        { name: 'slow-operation', arguments: {} },
         { timeout: 120_000 } // 2 minutes instead of the default 60 seconds
     );
     console.log(result.content);
@@ -581,7 +581,7 @@ let lastToken: string | undefined;
 const result = await client.request(
     {
         method: 'tools/call',
-        params: { name: 'long-running-task', arguments: {} }
+        params: { name: 'long-running-operation', arguments: {} }
     },
     {
         resumptionToken: lastToken,
@@ -596,18 +596,6 @@ console.log(result);
 
 For an end-to-end example of server-initiated SSE disconnection and automatic client reconnection with event replay, see [`ssePollingClient.ts`](https://github.com/modelcontextprotocol/typescript-sdk/blob/main/examples/client/src/ssePollingClient.ts).
 
-## Tasks (experimental)
-
-> [!WARNING]
-> The tasks API is experimental and may change without notice.
-
-Task-based execution enables "call-now, fetch-later" patterns for long-running operations (see [Tasks](https://modelcontextprotocol.io/specification/latest/basic/utilities/tasks) in the MCP specification). Instead of returning a result immediately, a tool creates a task that can be polled or resumed later. To use tasks:
-
-- Call {@linkcode @modelcontextprotocol/client!experimental/tasks/client.ExperimentalClientTasks#callToolStream | client.experimental.tasks.callToolStream(...)} to start a tool call that may create a task and emit status updates over time.
-- Call {@linkcode @modelcontextprotocol/client!experimental/tasks/client.ExperimentalClientTasks#getTask | client.experimental.tasks.getTask(...)} and {@linkcode @modelcontextprotocol/client!experimental/tasks/client.ExperimentalClientTasks#getTaskResult | getTaskResult(...)} to check status and fetch results after reconnecting.
-
-For a full runnable example, see [`simpleTaskInteractiveClient.ts`](https://github.com/modelcontextprotocol/typescript-sdk/blob/main/examples/client/src/simpleTaskInteractiveClient.ts).
-
 ## See also
 
 - [`examples/client/`](https://github.com/modelcontextprotocol/typescript-sdk/tree/main/examples/client) — Full runnable client examples

docs/client.md

@@ -495,19 +495,6 @@ server.registerTool(
 );
 ```
 
-## Tasks (experimental)
-
-> [!WARNING]
-> The tasks API is experimental and may change without notice.
-
-Task-based execution enables "call-now, fetch-later" patterns for long-running operations (see [Tasks](https://modelcontextprotocol.io/specification/latest/basic/utilities/tasks) in the MCP specification). Instead of returning a result immediately, a tool creates a task that can be polled or resumed later. To use tasks:
-
-- Provide a {@linkcode @modelcontextprotocol/server!index.TaskStore | TaskStore} implementation that persists task metadata and results (see {@linkcode @modelcontextprotocol/server!index.InMemoryTaskStore | InMemoryTaskStore} for reference).
-- Enable the `tasks` capability when constructing the server.
-- Register tools with {@linkcode @modelcontextprotocol/server!experimental/tasks/mcpServer.ExperimentalMcpServerTasks#registerToolTask | server.experimental.tasks.registerToolTask(...)}.
-
-For a full runnable example, see [`simpleTaskInteractive.ts`](https://github.com/modelcontextprotocol/typescript-sdk/blob/main/examples/server/src/simpleTaskInteractive.ts).
-
 ## Shutdown
 
 For stateful multi-session HTTP servers, capture the `http.Server` from `app.listen()` so you can stop accepting connections, then close each session transport:

docs/migration-SKILL.md

@@ -24,18 +24,17 @@ Most clients expect a server to be running. Start one from [`../server/README.md
 
 ## Example index
 
-| Scenario                                            | Description                                                                               | File                                                                                       |
-| --------------------------------------------------- | ----------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------ |
-| Interactive Streamable HTTP client                  | CLI client that exercises tools/resources/prompts, notifications, elicitation, and tasks. | [`src/simpleStreamableHttp.ts`](src/simpleStreamableHttp.ts)                               |
-| Backwards-compatible client (Streamable HTTP → SSE) | Tries Streamable HTTP first, falls back to legacy SSE on 4xx responses.                   | [`src/streamableHttpWithSseFallbackClient.ts`](src/streamableHttpWithSseFallbackClient.ts) |
-| SSE polling client (legacy)                         | Polls a legacy HTTP+SSE server and demonstrates notification handling.                    | [`src/ssePollingClient.ts`](src/ssePollingClient.ts)                                       |
-| Parallel tool calls                                 | Runs multiple tool calls in parallel.                                                     | [`src/parallelToolCallsClient.ts`](src/parallelToolCallsClient.ts)                         |
-| Multiple clients in parallel                        | Connects multiple clients concurrently to the same server.                                | [`src/multipleClientsParallel.ts`](src/multipleClientsParallel.ts)                         |
-| OAuth client (interactive)                          | OAuth-enabled client (dynamic registration, auth flow).                                   | [`src/simpleOAuthClient.ts`](src/simpleOAuthClient.ts)                                     |
-| OAuth provider helper                               | Demonstrates reusable OAuth providers.                                                    | [`src/simpleOAuthClientProvider.ts`](src/simpleOAuthClientProvider.ts)                     |
-| Client credentials (M2M)                            | Machine-to-machine OAuth client credentials example.                                      | [`src/simpleClientCredentials.ts`](src/simpleClientCredentials.ts)                         |
-| URL elicitation client                              | Drives URL-mode elicitation flows (sensitive input in a browser).                         | [`src/elicitationUrlExample.ts`](src/elicitationUrlExample.ts)                             |
-| Task interactive client                             | Demonstrates task-based execution + interactive server→client requests.                   | [`src/simpleTaskInteractiveClient.ts`](src/simpleTaskInteractiveClient.ts)                 |
+| Scenario                                            | Description                                                                        | File                                                                                       |
+| --------------------------------------------------- | ---------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------ |
+| Interactive Streamable HTTP client                  | CLI client that exercises tools/resources/prompts, notifications, and elicitation. | [`src/simpleStreamableHttp.ts`](src/simpleStreamableHttp.ts)                               |
+| Backwards-compatible client (Streamable HTTP → SSE) | Tries Streamable HTTP first, falls back to legacy SSE on 4xx responses.            | [`src/streamableHttpWithSseFallbackClient.ts`](src/streamableHttpWithSseFallbackClient.ts) |
+| SSE polling client (legacy)                         | Polls a legacy HTTP+SSE server and demonstrates notification handling.             | [`src/ssePollingClient.ts`](src/ssePollingClient.ts)                                       |
+| Parallel tool calls                                 | Runs multiple tool calls in parallel.                                              | [`src/parallelToolCallsClient.ts`](src/parallelToolCallsClient.ts)                         |
+| Multiple clients in parallel                        | Connects multiple clients concurrently to the same server.                         | [`src/multipleClientsParallel.ts`](src/multipleClientsParallel.ts)                         |
+| OAuth client (interactive)                          | OAuth-enabled client (dynamic registration, auth flow).                            | [`src/simpleOAuthClient.ts`](src/simpleOAuthClient.ts)                                     |
+| OAuth provider helper                               | Demonstrates reusable OAuth providers.                                             | [`src/simpleOAuthClientProvider.ts`](src/simpleOAuthClientProvider.ts)                     |
+| Client credentials (M2M)                            | Machine-to-machine OAuth client credentials example.                               | [`src/simpleClientCredentials.ts`](src/simpleClientCredentials.ts)                         |
+| URL elicitation client                              | Drives URL-mode elicitation flows (sensitive input in a browser).                  | [`src/elicitationUrlExample.ts`](src/elicitationUrlExample.ts)                             |
 
 ## URL elicitation example (server + client)
 

docs/migration.md

@@ -490,7 +490,7 @@ async function errorHandling_timeout(client: Client) {
     //#region errorHandling_timeout
     try {
         const result = await client.callTool(
-            { name: 'slow-task', arguments: {} },
+            { name: 'slow-operation', arguments: {} },
             { timeout: 120_000 } // 2 minutes instead of the default 60 seconds
         );
         console.log(result.content);
@@ -530,7 +530,7 @@ async function resumptionToken_basic(client: Client) {
     const result = await client.request(
         {
             method: 'tools/call',
-            params: { name: 'long-running-task', arguments: {} }
+            params: { name: 'long-running-operation', arguments: {} }
         },
         {
             resumptionToken: lastToken,

docs/server.md

@@ -4,7 +4,7 @@ import { createServer } from 'node:http';
 import { createInterface } from 'node:readline';
 import { URL } from 'node:url';
 
-import type { CallToolResult, ListToolsRequest, OAuthClientMetadata } from '@modelcontextprotocol/client';
+import type { ListToolsRequest, OAuthClientMetadata } from '@modelcontextprotocol/client';
 import { Client, StreamableHTTPClientTransport, UnauthorizedError } from '@modelcontextprotocol/client';
 import open from 'open';
 
@@ -209,7 +209,7 @@ class InteractiveOAuthClient {
         console.log('Commands:');
         console.log('  list - List available tools');
         console.log('  call <tool_name> [args] - Call a tool');
-        console.log('  stream <tool_name> [args] - Call a tool with streaming (shows task status)');
+        console.log('  stream <tool_name> [args] - (disabled; returns when the SEP-2663 tasks extension lands)');
         console.log('  quit - Exit the client');
         console.log();
 
@@ -232,7 +232,7 @@ class InteractiveOAuthClient {
                 } else if (command.startsWith('stream ')) {
                     await this.handleStreamTool(command);
                 } else {
-                    console.log("❌ Unknown command. Try 'list', 'call <tool_name>', 'stream <tool_name>', or 'quit'");
+                    console.log("❌ Unknown command. Try 'list', 'call <tool_name>', or 'quit'");
                 }
             } catch (error) {
                 if (error instanceof Error && error.message === 'SIGINT') {
@@ -358,62 +358,11 @@ class InteractiveOAuthClient {
             return;
         }
 
-        try {
-            // Using the experimental tasks API - WARNING: may change without notice
-            console.log(`\n🔧 Streaming tool '${toolName}'...`);
-
-            const stream = this.client.experimental.tasks.callToolStream(
-                {
-                    name: toolName,
-                    arguments: toolArgs
-                },
-                {
-                    task: {
-                        taskId: `task-${Date.now()}`,
-                        ttl: 60_000
-                    }
-                }
-            );
-
-            // Iterate through all messages yielded by the generator
-            for await (const message of stream) {
-                switch (message.type) {
-                    case 'taskCreated': {
-                        console.log(`✓ Task created: ${message.task.taskId}`);
-                        break;
-                    }
-
-                    case 'taskStatus': {
-                        console.log(`⟳ Status: ${message.task.status}`);
-                        if (message.task.statusMessage) {
-                            console.log(`  ${message.task.statusMessage}`);
-                        }
-                        break;
-                    }
-
-                    case 'result': {
-                        console.log('✓ Completed!');
-                        const toolResult = message.result as CallToolResult;
-                        for (const content of toolResult.content) {
-                            if (content.type === 'text') {
-                                console.log(content.text);
-                            } else {
-                                console.log(content);
-                            }
-                        }
-                        break;
-                    }
-
-                    case 'error': {
-                        console.log('✗ Error:');
-                        console.log(`  ${message.error.message}`);
-                        break;
-                    }
-                }
-            }
-        } catch (error) {
-            console.error(`❌ Failed to stream tool '${toolName}':`, error);
-        }
+        // The streaming-tool demo (callToolStream) was removed with the 2025-11
+        // experimental tasks (SEP-2663); it returns when the tasks extension lands.
+        void toolName;
+        void toolArgs;
+        console.log('Streaming tool demo removed with the 2025-11 experimental tasks (SEP-2663); returns when the tasks extension lands.');
     }
 
     close(): void {