Make task:"always" imply MUST

Author: LucaButBoring

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

@@ -116,7 +116,7 @@ This is to be interpreted as a fine-grained layer in addition to capabilities, f
 1. If a server's capabilities include `tasks.requests.tools.call: true`, then clients consider the value of `execution.task`, and handle it accordingly:
    1. If `execution.task` 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 `execution.task` is `"optional"`, clients **MAY** invoke the tool as a task or as a normal request.
-   1. If `execution.task` 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.
+   1. If `execution.task` is `"always"`, clients **MUST** invoke the tool as a task. Servers **MUST** return a `-32601` (Method not found) error if a client does not attempt to do so.
 
 ## Protocol Messages