API Reference

Settings, toolsets/tools, and the C++ toolbar helpers. The helper classes are static and driven by the toolbar - they are not Blueprint-exposed. Tool names below are the AI-facing names an agent calls through call_tool.

Settings

UCrimsonMCPSettings (module CrimsonCommonEditor) - Project Settings -> Crimson -> Crimson MCP.

Member	Type	Default	Description
`bEnableCrimsonMCP`	`bool`	`false`	Master switch for all Crimson MCP tooling. Read at startup; change requires an editor restart.
`bShowMCPToolbarButton`	`bool`	`true`	Adds the MCP split button (server status + this menu) to the play toolbar. Independent of `bEnableCrimsonMCP`: hiding the button leaves MCP working. Read when the toolbar is built; change requires an editor restart.
`IsEnabled()`	`static bool`	-	Convenience gate every Crimson editor module calls before registering tools.
`ShouldShowToolbarButton()`	`static bool`	-	Gate `CrimsonCommonEditor` calls before adding the toolbar button.

UCrimsonEditorUtilitiesSettings (module CrimsonEditorUtilities) - Project Settings -> Crimson -> Crimson Editor Utilities.

Member	Type	Default	Description
`bEnableSaveGameDeleter`	`bool`	`true`	Registers the Delete Save Game toolbar button at startup.
`bEnableCommonMaps`	`bool`	`true`	Registers the Common Maps toolbar button at startup. The button also hides itself when `CommonEditorMaps` is empty.
`CommonEditorMaps`	`TArray<FSoftObjectPath>`	empty	Maps shown in the Common Maps dropdown. Empty hides the button. Editable only while `bEnableCommonMaps` is on.

MCP toolsets and tools

Three UToolsetDefinition subclasses registered by CrimsonEditorUtilities when Crimson MCP is enabled. Errors are reported to the agent via a script error.

Toolset	Tool	Description
`CrimsonSourceToolset`	`ReadFile`	Reads a text file in the project or engine tree and returns its contents (path must stay inside those roots).
`CrimsonSourceToolset`	`ListFiles`	Lists files in a project directory, with optional extension filter and recursion.
`CrimsonPluginToolset`	`ListPlugins`	Summarizes every plugin under the project Plugins folder: name, description, and module types.
`CrimsonPluginToolset`	`ValidateDependencies`	Audits all `*.Build.cs` for the cardinal rule (no Crimson-to-Crimson deps except CrimsonCommon / CrimsonSaveSystem).
`CrimsonPluginToolset`	`ScaffoldPlugin`	Generates a complete new Crimson plugin from template, applying the project conventions.
`CrimsonAssetToolset`	`FindAssets`	Queries the Asset Registry for assets of a UClass (including Blueprint subclasses).
`CrimsonAssetToolset`	`InspectAsset`	Loads an asset by package path and returns every UPROPERTY value.
`CrimsonAssetToolset`	`CreateAsset`	Creates a DataAsset or Blueprint asset in the Content Browser.
`CrimsonAssetToolset`	`SetAssetProperty`	Sets one UPROPERTY on an asset (Blueprint CDO for Blueprints) and saves it.
`CrimsonAssetToolset`	`FindTags`	Lists registered GameplayTags matching a prefix.

Names come from reflection

A toolset's name is its UToolsetDefinition class name and a tool's name is its function name; agents call them as Toolset.Tool. Confirm the exact live names with list_toolsets / describe_toolset.

Toolbar helpers (C++, static)

Class	Function	Description
`FCrimsonSaveGameDeleteUtility`	`HasPlayWorld()` / `HasNoPlayWorld()`	PIE-session checks used to gate the Delete Save Game button.
`FCrimsonSaveGameDeleteUtility`	`DeleteDirectoryAbsolute_Clicked(AbsolutePath)`	Deletes a save sub-directory. Absolute, because the save root is not necessarily `Saved/SaveGames/`.
`FCrimsonSaveGameDeleteUtility`	`DeleteSaveFileAbsolute_Clicked(AbsolutePath)`	Deletes a single `.sav` file.
`FCrimsonSaveGameDeleteUtility`	`DeleteFileGroup_Clicked(Name, Paths)`	Deletes every file in one group - the Delete All entry under a slot heading.
`FCrimsonSaveGameDeleteUtility`	`GetSaveFilesDropdown()`	Builds the Delete Save Game dropdown: directory tree plus root files, grouped by a registered `ICrimsonFileGroupProvider` when one exists.
`FCrimsonCommonMapsUtility`	`CanShowCommonMaps()`	True when not in PIE and at least one map is configured.
`FCrimsonCommonMapsUtility`	`GetCommonMapsDropdown()`	Builds the Common Maps dropdown from `CommonEditorMaps`.

Authoring your own MCP tools

To add MCP tools to a different Crimson plugin, use the shared base in CrimsonCommonEditor - see CrimsonCommon -> How-To: Add MCP Tools to a Plugin. Always gate registration on UCrimsonMCPSettings::IsEnabled() so the master switch keeps cascading.

MCP button and menu live in CrimsonCommon

The MCP toolbar button, FCrimsonMCPToolingUtility, and UCrimsonMCPSettings all live in CrimsonCommonEditor, not here - they configure suite-wide MCP state that every Crimson plugin reads, so they must exist for projects without this optional plugin. This plugin contributes the three toolsets above and nothing else MCP-related.

See CrimsonCommon -> API Reference -> Editor tooling, CrimsonCommon -> How-To: Manage MCP Toolsets, and CrimsonCommon -> Concept: How Crimson MCP Works.