Forge — UE5 Dev Agent

An AI-powered debugging and architecture assistant for Unreal Engine 5 C++ developers.

Forge diagnoses crashes, reviews code, spots multiplayer security vulnerabilities, and guides architecture decisions — powered by 30 knowledge files covering the full UE5 C++ ecosystem.

"Paste nothing. Forge reads it."

With MCP active, Forge reads your Output Log, build errors, and C++ files directly from your editor. No copy-paste, no context switching.

What Forge Does

OOM-Safe crash & error diagnosis — Forge reads 5GB+ Output Logs using memory-safe streaming queues (zero RAM bloat), categorizes errors, and gives you the root cause in seconds
Code review — safety, UE5 standards, performance, multiplayer security scan
Architecture consulting — "where does this go?" with decision tables
System analysis — paste multiple files, Forge analyzes them as a unified system
Version migration warnings — tells you what breaks when upgrading UE versions
Multiplayer security scan — unauthorized Server RPCs, unreplicated state, ownership issues
Teaching mode — explains why a bug happened, not just the fix
Session memory — remembers previously found issues across conversations
Accessibility (VI) mode — full screen-reader support for visually impaired developers

Setup (5 minutes)

Step 1 — Clone

git clone https://github.com/TheForgeDev/forge-ue5
cd forge-ue5

Step 2 — Install

pip install mcp httpx

Step 3 — Enable Remote Control API in UE5

Edit → Plugins → Remote Control API → Enable → Restart Editor

Step 4 — Configure Claude Desktop

Open your Claude Desktop config file:

Windows: %APPDATA%\Claude\claude_desktop_config.json
macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

Add Forge:

{
  "mcpServers": {
    "forge-ue5": {
      "command": "python",
      "args": ["C:/forge-ue5/server.py"],
      "env": {
        "UE_PROJECT_PATH": "C:/MyUE5Project"
      }
    }
  }
}

Replace paths with your actual locations.

Step 5 — Restart Claude Desktop

Forge will appear as a connected tool. No files need to be uploaded to Claude Projects.

Step 6 — Start your first conversation

UE5 version: 5.4
Platform: PC
Project type: multiplayer game
Experience: intermediate C++

How It Works

Lazy Knowledge Loading

Forge doesn't load all 30 knowledge files upfront. Instead, it loads only what's needed:

You: "My GAS ability isn't activating after respawn"
Forge: reads knowledge/gas.md → analyzes your specific issue

You: "Now my Chaos Vehicle only goes backward"  
Forge: reads knowledge/chaos_vehicles.md → different module, loaded fresh

Token usage:

Without MCP (manual): ~150K tokens (all files loaded)
With MCP lazy loading: ~10-15K tokens per conversation

The "Brain" vs The "Nervous System"

Claude is the reasoning engine — but out-of-the-box LLMs hallucinate UE5 C++ APIs. Forge acts as the nervous system: it provides the eyes (Remote Control API), the hands (file reading), and the strict rulebook (30 specialized knowledge files) so the LLM never guesses — it references.

Session Memory

Forge remembers what it finds across conversations:

Week 1: Fixed InitAbilityActorInfo missing in MyCharacter.cpp → saved

Week 2: Analyzing MyVehicle.cpp
Forge: "InitAbilityActorInfo was also missed in MyCharacter.cpp 
        (March 14). Checking MyVehicle.cpp for the same pattern..."

Session data is stored locally in .forge_session.json — never leaves your machine.

Available Tools

| Tool | What it does | |---|---| | read_knowledge(topic) | Load a knowledge module on demand | | get_project_info | UE5 version, project name, connection status | | analyze_output_log | Read and categorize errors from Output Log | | get_build_errors | LNK, C2xxx, UHT compiler errors | | get_blueprint_errors | Blueprint compile failures | | get_active_plugins | Active plugins from .uproject | | get_cpp_file(path) | Read a C++ file for code review | | get_crash_dump | Most recent crash report | | get_shader_errors | Material/shader compilation failures | | read_saved_log(n) | Read a specific log from Saved/Logs/ | | get_session_memory | Load previously found issues for this project | | save_session_finding | Save a finding to session memory |

Knowledge Base (30 Modules)

| Topic keyword | Coverage | |---|---| | gas | GAS setup, InitAbilityActorInfo, AttributeSet, replication | | multiplayer | Replication, RPC, authority, Online Subsystem | | security | Server RPC validation, exploit patterns, ownership | | vehicle | Chaos Vehicles setup, 7 error patterns | | save | Save/Load system, serialization, inventory | | animation | IK Retargeter, Motion Matching, Mixamo | | blueprint | All UPROPERTY/UFUNCTION specifiers | | architecture | GameMode/State/Controller decisions, Subsystems | | devenv | VS setup, Live Coding, IntelliSense | | lumen | Lumen/Nanite console variables, artifacts | | material | Materials, shaders, HLSL custom nodes | | world_partition | Streaming, data layers, HLOD | | input | Enhanced Input System, migration from legacy | | ui | UMG, BindWidget, CommonUI, 3D widgets | | packaging | Cook errors, "works in editor fails packaged" | | threading | Async patterns, TWeakObjectPtr in lambdas | | versions | UE5.0→5.5 breaking changes | | ai | Behavior Trees, EQS, custom tasks | | audio | MetaSounds, attenuation, audio debugging | | plugin | Plugin development, module boilerplate |

Example Conversations

Crash diagnosis:

"My game crashed. Can you analyze the log?"
→ Forge reads Output Log directly, categorizes errors, gives root cause

Code review:

"Review MyCharacter.cpp for multiplayer security issues"
→ Forge reads the file, runs security scan, flags RPC validation gaps

System analysis:

"Here are my GAS setup files — what will break as the project grows?"
→ Forge loads gas knowledge, analyzes files as a system, flags weak points

Version migration:

"I'm upgrading from UE5.3 to 5.4. What should I check?"
→ Forge loads versions knowledge, lists breaking changes relevant to your code

Accessibility Mode

For developers using screen readers (NVDA, JAWS, VoiceOver):

enable VI mode

Output becomes screen-reader friendly: code blocks described before displaying, errors explained in 3 structured layers, symbols replaced with words.

Disable with: disable VI mode

Works with Other AI Tools

server.py is a standard MCP server — works with any MCP-compatible client:

| Tool | Config location | |---|---| | Claude Desktop | %APPDATA%/Claude/claude_desktop_config.json | | Cursor | .cursor/mcp.json in project root | | Windsurf | ~/.config/windsurf/mcp.json | | VS Code | .vscode/mcp.json |

Note: Knowledge files and session memory work best with Claude, which understands the Forge system prompt context.

Forge vs Other UE5 AI Tools

| | Forge | UnrealClaude / unreal-mcp | |---|---|---| | Editor control (spawn actors, edit BP) | Planned (Phase 2) | Yes | | Crash log analysis | Yes | Partial | | UE version migration warnings | Yes | No | | Multiplayer security scan | Yes | No | | Architecture consulting | Yes | No | | Session memory | Yes | No | | Teaching mode | Yes | No | | Deep domain knowledge (30 modules) | Yes | No | | Token efficient (lazy loading) | Yes | N/A | | Installation | pip install | Plugin + npm |

Forge and editor control tools are complementary. Use both for best results.

Contributing

Pull requests welcome. To add a knowledge module:

Create knowledge/UE5_[Domain]_Guide_v1.0.md
Add the topic → filename mapping to KNOWLEDGE_MAP in server.py
Follow the existing format: overview, C++ setup, common errors, debug commands, agent rules
All content in English
Submit PR with a brief description

Roadmap

[x] Core knowledge base (30 files)
[x] MCP server with diagnosis tools
[x] Lazy knowledge loading
[x] Session memory
[ ] Editor control tools (Phase 2 — fork of UnrealClaude)
[ ] Git diff analysis ("what will this commit break?")
[ ] Pre-commit security scan
[ ] Test suite — 25-question benchmark
[ ] Phase 3: Active Control Architect (v2.0) — Evolving beyond passive debugging. Integrating Model Predictive Control (MPC) solvers (OSQP) to let Forge actively optimize robotic locomotion, advanced vehicle dynamics, and GAS-driven physics directly in the engine.

License

MIT — free to use, modify, and distribute. Token costs are always the user's own.

Forge grew from a simple question: why does the same GAS crash take every developer hours to find, when the answer is always the same? The goal: put 30 files of accumulated UE5 C++ knowledge into every developer's context window.

Forge Ue5

Install / Use

README