Change taskHint to enum

Author: LucaButBoring

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

@@ -108,10 +108,11 @@ Tool calls are given special consideration for the purpose of task augmentation.
 
 This is to be interpreted as a fine-grained layer in addition to capabilities, following these rules:
 
-1. If a server's capabilities include `tasks.requests.tools.call: false`, then clients **MUST NOT** attempt to use task augmentation on that server's tools, even if they declare tool-level support via `annotations.taskHint`.
+1. If a server's capabilities include `tasks.requests.tools.call: false`, then clients **MUST NOT** attempt to use task augmentation on that server's tools, regardless of the `taskHint` value.
 1. If a server's capabilities include `tasks.requests.tools.call: true`, then clients consider the value of `taskHint`, and handle it accordingly:
-   1. If `taskHint` is not present or `false`, clients **MUST NOT** attempt to invoke the tool as a task. Servers **SHOULD** return a `-32601` (Method not found) error if a client attempts to do so.
-   1. If `taskHint` is `true`, clients **SHOULD** attempt to invoke the tool as a task. Servers **MAY** return a `-32601` (Method not found) error if a client does not attempt to do so.
+   1. If `taskHint` is not present or `"never"`, clients **MUST NOT** attempt to invoke the tool as a task. Servers **SHOULD** return a `-32601` (Method not found) error if a client attempts to do so. This is the default behavior.
+   1. If `taskHint` is `"optional"`, clients **MAY** invoke the tool as a task or as a normal request.
+   1. If `taskHint` is `"always"`, clients **SHOULD** invoke the tool as a task. Servers **MAY** return a `-32601` (Method not found) error if a client does not attempt to do so.
 
 ## Protocol Messages
 

docs/specification/draft/schema.mdx

@@ -1205,13 +1205,17 @@ export interface ToolAnnotations {
   openWorldHint?: boolean;
 
   /**
-   * If true, this tool is expected to support task-augmented execution.
+   * Indicates whether this tool supports task-augmented execution.
    * This allows clients to handle long-running operations through polling
    * the task system.
    *
-   * Default: false
+   * - "never": Tool does not support task-augmented execution (default when absent)
+   * - "optional": Tool may support task-augmented execution
+   * - "always": Tool requires task-augmented execution
+   *
+   * Default: "never"
    */
-  taskHint?: boolean;
+  taskHint?: "never" | "optional" | "always";
 }
 
 /**