fix(mcp): enforce token scopes independently of RBAC

docs/admin_docs/security/security.mdx

@@ -400,7 +400,7 @@ Once enabled, each user manages their own keys from their profile page:
 1. Open the user menu (top-right) and click **Info** to navigate to the User Info page
 2. Expand the **API Keys** section
 3. Click **+ API Key**
-4. Enter a name and (optionally) an expiration date
+4. Enter a name and optionally select resource scopes
 5. Copy the generated token — it is shown only once
 
 Only users with the `can_read` and `can_write` permissions on `ApiKey` (granted by default to Admins) can manage API keys.
@@ -415,6 +415,18 @@ Authorization: Bearer <your-api-key>
 
 This works for all REST API endpoints and the MCP server. The request is executed with the permissions of the user who created the key.
 
+#### API Key Scopes
+
+The creation dialog can restrict an API key to MCP resource actions such as
+`superset:dashboard:read` or `superset:chart:write`. A scope is an additional
+restriction: it never grants a permission that the creating user does not
+already have through Superset RBAC. Write scopes also cover update and delete
+operations for that resource; `superset:sqllab:write` covers SQL execution.
+
+Keys created without scopes retain legacy RBAC-only behavior. The scoped-key
+restrictions described here are enforced by the MCP server; regular REST API
+routes continue to apply their existing Superset RBAC checks.
+
 #### Use Cases
 
 - **CI/CD pipelines** — automated chart/dashboard exports and imports