Skills

Agent Skills — task guidance served by the editor

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Tools expose operations in Unreal Editor; Skills define how to approach a task using those operations. AgentMcp serves Skills through the editor's MCP server instead of locking instructions to Claude Code. Inspired by Unreal Engine 5.8's Agent Skill concept, it provides a separate Markdown-based implementation for earlier engine versions.

Why separate Tools and Skills?

The first Dungeon UI sample could be authored through Widget Blueprint tools, but it duplicated repeated elements and embedded style values in individual widgets. Being able to create a widget tree does not decide whether that tree is maintainable.

The UMG tools therefore handle inspecting and changing Widget Trees, while the umg-authoring Skill describes reusable components, C++ BindWidget contracts, data-driven lists, and in-game visual review.

Layer	Responsibility	Example
MCP Tool	Inspect or modify actual project state	umg_inspect, umg_add_widgets, blueprint_compile, viewport_capture
Agent Skill	Guide the order of investigation, authoring and review	Find existing components first; use reusable entry widgets for repeated lists
Project configuration	Replace built-in guidance with team conventions	Provide a project-level Skill named umg-authoring

How the Dungeon UI work separated Tools and Skills

How an agent uses a Skill

Agent connects to the editor's MCP server
  → Reads available Skill names and descriptions in server instructions
  → Requests a matching Skill with skills_get
  → Reads SKILL.md and any needed supporting files
  → Invokes actual MCP Tools following those instructions
  → Reviews the result through compilation, PIE and captures

For instance, before authoring game UI:

{"name": "umg-authoring"}

Call skills_get with these arguments to receive the SKILL.md body (without YAML front matter) and a list of supporting files. To read an additional file:

{"name": "perf-investigation", "file": "references/scene-runner.md"}

• skills_list: Returns currently discovered names, descriptions, paths, overridden paths and reasons for skipped files.
• skills_get: Reads a Skill body or a text file within that Skill folder. files lists other available paths; bTruncated indicates truncated output.
• A Skill is guidance for selecting and using tools. Reading it does not create or edit assets by itself.

Included Skills

Skill	Scope
umg-authoring	Reusable Widget Blueprints, BindWidget, data-driven lists, visual review in PIE
ui-style-system	Theme Data Assets, style tokens, extraction and application, UI Kit Gallery
ui-art-requests	Art requests and review, texture import and UMG integration
blueprint-graphs	Blueprint class, member and graph edits, runtime checks
perf-investigation	Repeated fixed-scene runs, CSV and Insights analysis, before/after comparisons

The performance Skill includes scripts for measuring a standalone game with the editor closed, as well as a scene-runner reference. Scripts execute the measurements; MCP performance tools interpret the generated files. Performance workflow

Add or customize project Skills

Skills are searched in this order. A later Skill with the same name replaces the earlier one completely; their instructions are not merged.

1. Plugins/AgentMcp/Skills — built-in plugin Skills
2. <project>/AgentMcp/Skills — project-specific Skills
3. SkillDirectories — additional configured locations, in the configured order. Relative paths are resolved from the project root.

To add a project-specific Skill, create AgentMcp/Skills/studio-ui/SKILL.md:

---
name: studio-ui
description: Apply this project's UI naming and review rules when editing UMG screens.
---

# Studio UI

1. Inspect existing Widget Blueprints and their C++ parent classes first.
2. Follow this project's naming and component conventions.
3. Compile changes and review the actual screen in PIE.

The folder and name must match. Names use lowercase ASCII letters, digits and hyphens. The description tells agents when the guidance applies. Additional roots can be configured through SkillDirectories.

To see dynamic loading: Use skills_list to find studio-ui, read it with skills_get, edit its SKILL.md without restarting Unreal Editor, and call the same skills_get again. The updated body is returned. To override the built-in umg-authoring Skill instead, create AgentMcp/Skills/umg-authoring/SKILL.md with matching front matter.

Discovery has two moments. skills_list and skills_get rescan directories and read files on each request. However, the Skill list embedded in the initial MCP server instructions is generated during initialization. Newly added names and descriptions may require an MCP client reconnection to appear in those initial instructions.

Discovering Skills from Claude Code and Codex

Skills advertised by the server are distinct from Skills discovered locally by an agent client. This repository provides small bridge files carrying each built-in Skill's name and description:

• Claude Code: .claude/skills
• Codex: .agents/skills

When the client selects one of those local bridges, it is instructed to call skills_get. The actual instructions remain in one plugin-owned SKILL.md. Those bridge files are not automatically installed in other projects or clients; add the appropriate bridge if that discovery behavior is desired.

Implementation

Source	Responsibility
AgentMcpSkills.cpp	ScanSkills searches locations in order; ParseSkillFile parses front matter and body
AgentMcpSkillTools.cpp	skills_list / skills_get and on-demand file reads
AgentMcpSkillTools.h	Reflected MCP Tool declarations and structured results
AgentMcpSettings.h	SkillDirectories and result-size settings

skills_get serves text files only from within the selected Skill directory. Parent-directory traversal via .., hidden files and binary content are rejected; responses have size limits.

Unreal Engine 5.8 exposes an asset/class-based Skill interface through UAgentSkill and UAgentSkillToolset. AgentMcp instead implements discovery and loading of Markdown files. It does not port the UE 5.8 Skill classes or claim to expose the same API. UE 5.8 UAgentSkill · UAgentSkillToolset