Make task IDs exclusively server-generated

Author: LucaButBoring

docs/specification/draft/basic/utilities/tasks.mdx

@@ -6,7 +6,7 @@ title: Tasks
 
 <Info>**Protocol Revision**: draft</Info>
 
-The Model Context Protcol (MCP) allows requestors (which can be either clients or servers, depending on the direction of communication) to augment their requests with **tasks**. Tasks are durable state machines that carry information about the underlying execution state of the request they wrap, and are intended for requestor polling and deferred result retrieval. Each task is uniquely identifiable by a requestor-generated **task ID**.
+The Model Context Protcol (MCP) allows requestors (which can be either clients or servers, depending on the direction of communication) to augment their requests with **tasks**. Tasks are durable state machines that carry information about the underlying execution state of the request they wrap, and are intended for requestor polling and deferred result retrieval. Each task is uniquely identifiable by a receiver-generated **task ID**.
 
 ## User Interaction Model
 
@@ -90,7 +90,7 @@ Task-augmented requests follow a two-phase response pattern that differs from no
 - **Normal requests**: The server processes the request and returns the actual operation result directly.
 - **Task-augmented requests**: The server accepts the request and immediately returns a `CreateTaskResult` containing task metadata. The actual operation result becomes available later through `tasks/result` after the task completes.
 
-To create a task, requestors send a request with the `modelcontextprotocol.io/task` key included in `_meta`, with a `taskId` value representing the task ID. Requestors **MAY** include a `keepAlive`, with a value representing how long after completion the requestor would like the task results to be kept for.
+To create a task, requestors send a request with the `modelcontextprotocol.io/task` key included in `_meta`. Requestors **MAY** include a `keepAlive` value representing how long after completion the requestor would like the task results to be kept for.
 
 **Request:**
 
@@ -106,7 +106,6 @@ To create a task, requestors send a request with the `modelcontextprotocol.io/ta
     },
     "_meta": {
       "modelcontextprotocol.io/task": {
-        "taskId": "786512e2-9e0d-44bd-8f29-789f320fe840",
         "keepAlive": 60000
       }
     }
@@ -358,8 +357,8 @@ These requirements apply to all parties that support receiving task-augmented re
 ### Task ID Requirements
 
 1. Task IDs **MUST** be a string value.
-1. Task IDs **SHOULD** be unique across all tasks controlled by the receiver.
-1. The receiver of a request with a task ID in its `_meta` **MAY** validate that the provided task ID has not already been associated with a task controlled by that receiver.
+1. Task IDs **MUST** be generated by the receiver when creating a task.
+1. Task IDs **MUST** be unique across all tasks controlled by the receiver.
 
 ### Task Status Lifecycle
 
@@ -675,15 +674,13 @@ When augmenting a request with task execution, the `modelcontextprotocol.io/task
 ```json
 {
   "modelcontextprotocol.io/task": {
-    "taskId": "786512e2-9e0d-44bd-8f29-789f320fe840",
     "keepAlive": 60000
   }
 }
 ```
 
 Fields:
 
-- `taskId` (string, required): Client-generated unique identifier for the task
 - `keepAlive` (number, optional): Requested duration in milliseconds to retain results after completion
 
 ### Related Task Metadata
@@ -713,7 +710,6 @@ Receivers **MUST** return standard JSON-RPC errors for the following protocol er
 
 - Invalid or nonexistent `taskId` in `tasks/get`, `tasks/list`, `tasks/result`, or `tasks/delete`: `-32602` (Invalid params)
 - Invalid or nonexistent cursor in `tasks/list`: `-32602` (Invalid params)
-- Request with a `taskId` that was already used for a different task (if the receiver validates task ID uniqueness): `-32602` (Invalid params)
 - Attempting to retrieve result when task is not in `completed` status: `-32602` (Invalid params)
 - Receiver rejects a `tasks/delete` request: `-32600` (Invalid request)
 - Internal errors: `-32603` (Internal error)
@@ -765,19 +761,6 @@ Receivers are not obligated to retain task metadata indefinitely. It is complian
 }
 ```
 
-**Example: Duplicate task ID (if receiver validates uniqueness)**
-
-```json
-{
-  "jsonrpc": "2.0",
-  "id": 73,
-  "error": {
-    "code": -32602,
-    "message": "Task ID already exists: 786512e2-9e0d-44bd-8f29-789f320fe840"
-  }
-}
-```
-
 **Example: Task deletion rejected by receiver**
 
 ```json

docs/specification/draft/schema.mdx

@@ -1175,11 +1175,6 @@ export type TaskStatus =
  * @category tasks
  */
 export interface TaskMetadata {
-  /**
-   * Client-generated unique identifier for the task.
-   */
-  taskId: string;
-
   /**
    * Requested duration in milliseconds to retain results after completion.
    */