[brandonkelly]

Summary

The elements_* tools rejected categories, tags, and global sets: Unsupported element type [craft\elements\Category]. Supported types: entries, assets, users, addresses. Craft 5 sites still use all three heavily. On craftcom, for example, the Blog's postCategory field relates to categories, so agents could only refer to them by raw ID.

 ElementAdapterRegistry defaults
   EntryAdapter, AssetAdapter, UserAdapter, AddressAdapter
+  CategoryAdapter    categories   list/get/create/update/delete/duplicate (copy); criteria group, groupId, slug; context {groupId, siteId}
+  TagAdapter         tags         list/get/create/update/delete; criteria group, groupId; context {groupId}
+  GlobalSetAdapter   globalSets   list/get/update content only; criteria handle

Each adapter uses Craft's own element permissions (saveCategories:<uid> and so on), plus the editSite:<uid> check the categories and globals controllers make on multi-site installs, for saving and for deleting categories. Like entries, categories load by ID or UID even when disabled, including saved drafts; tags load even when disabled. Tags allow everyone, which matches Tag::canSave()/canDelete().

Global sets need an extra rule. GlobalSet::canSave() returns true for every user, because GlobalsController enforces editGlobalSet:<uid> itself. elements_restore and elements_validate find elements through ElementLifecycle with plain Authorization checks, so the rule lives in Authorization rather than only in the adapter:

Authorization::allows(user, ability, globalSet)
  if ability != view and (set is trashed or user lacks editGlobalSet:<uid>)
    deny
  else native canX()

Deleted global sets are config-backed. They come back through project config, so restoring the element by itself would leave an orphan, and elements_restore refuses it even for admins. Creating, renaming, and deleting sets is left to Settings → Globals, and elements_schema notes say so.

Categories and tags are now summarized as {type, id, status} in nested dot-path output, like other fetchable types. Before, they were fully serialized.

Craft 6: not applicable. In craftcms/cms 6.x, categories, tags, and global sets exist only in yii2-adapter/legacy, and the Craft 6 MCP server has no adapters for them.

Evidence

New ElementAdaptersTest:

categories: elements_create {groupId, title: "Releases"} -> elements_list {group: mcpTopics} ids == [it]
            disable it -> elements_get title == "Releases"
tags:       elements_create {groupId, title: "craft6"}   -> elements_list {groupId} titles == ["craft6"]
globalSets: user without editGlobalSet: elements_update and elements_get fail
            with editGlobalSet:<uid>:    elements_update sets plainTextField3
            admin: elements_restore on a deleted set fails

• Before: ToolCallException: Unsupported element type [craft\elements\Category]. Supported types: entries, assets, users, addresses. (and the same for globalSets)
  After: OK (2 tests, 10 assertions)
• Mutation checks: without the Authorization rule, a user without permission can update the global set. Without the trashed check, an admin can restore a deleted set. The test fails in both cases.

vendor/bin/codecept run unit mcp passes (72 tests). ECS, Rector, and PHPStan are clean.

[Copilot]

🟡 Changes recommended

Category deletion lacks a site-access check, allowing users with group delete permission to delete or hard-delete categories in sites they cannot access.

3 open issues

• Enforce site access when deleting categories · New
• Allow disabled categories and saved drafts in element lookups · New
• Honor context.siteId in new-category schema requests · New

What changed in this PR

Extends Craft 5’s elements_* MCP tools to support categories, tags, and global sets through the existing adapter system.

Changes:

• Registers category, tag, and global-set adapters with type-specific schemas and operations.
• Restricts global-set changes to permitted content updates and blocks restoration of deleted sets.
• Adds integration coverage and changelog entries for the new support.

File	Description
tests/​unit/​mcp/​ElementAdaptersTest.php	Tests category/tag operations and global-set permission restrictions.
src/​mcp/​elements/​ElementAdapterRegistry.php	Registers the three new adapters.
src/​mcp/​elements/​adapters/​TagAdapter.php	Adds tag criteria, attribute schemas, and field-schema context.
src/​mcp/​elements/​adapters/​GlobalSetAdapter.php	Supports global-set content updates with site authorization.
src/​mcp/​elements/​adapters/​CategoryAdapter.php	Adds category operations, copy duplication, and site authorization.
src/​mcp/​Authorization.php	Enforces global-set edit permissions and blocks trashed-set mutations.
CHANGELOG.md	Documents the expanded MCP support and new adapter classes.

_{Review effort: Balanced}

[brandonkelly]

Fixed in c3ac2a3: CategoryAdapter::canDelete() now requires editSite for the category's site on multi-site installs, as well as the native delete permission. This matches CategoriesController::_enforceEditCategoryPermissions(). One correction: Category::canView() doesn't check site access, so the check is explicit rather than going through canView().

[brandonkelly]

Fixed in c3ac2a3: categories now load with drafts(null)->status(null), as EntryAdapter does, and tags with status(null). Listing defaults are unchanged. The test now disables the category and reads it back. It fails without this change ("Category not found.").