ue-mcp-native-cpp

ue-mcp-native-cpp is a skill for Claude Code, Codex from db-lyon/ue-mcp. It costs 83 tokens per session (977 once invoked), scanned A, original, MIT.

A workflow guide for writing native C++ classes in an Unreal Engine project through ue-mcp. It covers creating Unreal classes, editing their header and source files, and compiling the result.

In plain words
What is it for?
Use it to create classes, add properties or other declarations, modify C++ files, add module dependencies, and compile changes with Unreal's build or Live Coding tools.
Why use it?
It gives coding agents a repeatable way to add or change Unreal C++ without relying on Python or manually using the editor. It also helps choose the right compile method and module.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/db-lyon/ue-mcp/ue-mcp-native-cpp
Any agent
npx skills add db-lyon/ue-mcp --skill ue-mcp-native-cpp
Clone the repo
git clone --depth 1 https://github.com/db-lyon/ue-mcp

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for ue-mcp-native-cpp

README.md
[![agentmods](https://agentmods.dev/badge/skills/db-lyon/ue-mcp/ue-mcp-native-cpp.svg)](https://agentmods.dev/skills/db-lyon/ue-mcp/ue-mcp-native-cpp)
Your own site
<a href="https://agentmods.dev/skills/db-lyon/ue-mcp/ue-mcp-native-cpp"><img src="https://agentmods.dev/badge/skills/db-lyon/ue-mcp/ue-mcp-native-cpp.svg" alt="Measured on agentmods" height="20"></a>
Per session 83 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 977 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00083 $0.00977
Opus 5 $0.00042 $0.00489
Sonnet 5 $0.00017 $0.00195
Haiku 4.5 $0.00008 $0.00098

Measured 5d ago against content hash 40abe38dceda, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ue-mcp-native-cpp scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/ue-mcp-native-cpp/SKILL.md · 51 lines

How it starts

The opening of the file, as written. The whole thing — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ue-mcp native C++ authoring

The project tool wraps GameProjectUtils::AddCodeToProject and ILiveCodingModule so agents can author native C++ end-to-end without Python or the editor UI.

The authoring loop

  1. Pick a module. project(action="list_project_modules") enumerates the project's native modules (name, host type, source path). Feed the module name into create_cpp_class.
  2. Create the class. project(action="create_cpp_class", className, parentClass?, moduleName?, classDomain?, subPath?) writes .h and .cpp using the same engine template that File → New C++ Class uses. The class-name prefix (A, U, F) is derived from parentClass - pass the bare name ("BotSpawner", not "ABotSpawner").
  3. Inspect the generated files. project(action="read_cpp_header", headerPath=...) and project(action="read_cpp_source", sourcePath=...). Both paths are relative to Source/ or absolute within it.
  4. Append declarations and bodies. project(action="write_cpp_file", path=..., content=...) writes the full file contents (scoped to the Source/ tree for safety). Read first, then write the amended content.
  5. Compile.
    • New UCLASSproject(action="build"). Live Coding doesn't reliably register brand-new UCLASSes; you need a full build and an editor restart. create_cpp_class surfaces this via needsEditorRestart in its response.
    • Existing UCLASS (editing method bodies, adding UPROPERTYs, etc.) → project(action="live_coding_compile", wait=true). Hot-patches method bodies without restart - the fast inner loop. Check live_coding_status first to confirm Live Coding is available and not already compiling.

Adding module dependencies

When you need a new module in a project's Build.cs:

  • project(action="add_module_dependency", moduleName=<target Build.cs>, dependency=<module to add>, access="public"|"private")
  • Deduplicates automatically. Creates the AddRange block if missing.
  • Rebuild afterwards (project(action="build")).

Read the full file on GitHub · 51 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 51 lines · 83 tokens per session scan A 40abe38dceda

Subscribe to this mod's changes

ue-mcp-native-cpp is a skill published in the GitHub repository db-lyon/ue-mcp (304 stars, last pushed today), licensed MIT. It adds 83 tokens to every session and 977 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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