Features:

NexusLink embeds an MCP (Model Context Protocol) server in the Unreal Editor, exposing project context and editor workflows to AI clients over Streamable HTTP (POST /stream, port 45000) and WebSocket (port 55000). Sessions are isolated via Mcp-Session-Id; multiple clients can connect concurrently.

109 atomic Capabilities plus 3 meta tools cover the full editor workflow: asset search/CRUD, Blueprints, Animation (Anim Blueprints, Montages, BlendSpaces, keyframes/curves), Materials and Material Functions, Structs, DataAssets/DataTables, UMG Widgets, Behavior Trees/Blackboards, Enhanced Input, Sequencer, StateTree/MVVM, Niagara, Control Rig/IK Rig, MetaSound (Source/Patch), PCG, PoseSearch, Physics Assets, EQS, and more.

Runtime (PIE) control: list/spawn/destroy Actors, read/write Actor and Widget properties, drive AnimInstance/Montages, Behavior Tree blackboard, and optional Gameplay Ability System snapshots.

Lua runtime tooling (optional, requires UnLua): eval/dofile/hotreload, inspect globals, stack, metatables, and memory.

Two discovery modes: SearchMode (3 meta tools plus intent-based search_capabilities) and MultiTool (each enabled Capability exposed as its own tool). Broadcasts notifications/tools/list_changed on configuration change.

Per-Capability enable/disable, response payload compaction, viewport/UMG screenshot capture, output-log querying, console command execution, and an AI feedback loop (local logging, Markdown export, GitHub issue prefill).

MCP server is off by default; toggling it in Editor Preferences starts/stops HTTP and WebSocket instantly with no editor restart. Automatic port allocation and zero-scan instance registration for IDE proxies (NexusRider, NexusVSCode, NexusDesktop).

Code Modules:

NexusLink (Editor)

NexusLinkTests (DeveloperTool)

Number of Blueprints: 0

Number of C++ Classes: 271

Network Replicated: No (editor-only tooling; not shipped into packaged builds)

Supported Development Platforms: Windows

Supported Target Build Platforms: N/A (Editor-only plugin; not included in packaged/runtime builds)

Supported Engine Versions: UE 4.26 through UE 5.8 (tested on 4.26, 4.27, 5.0, 5.1, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8)

Dependencies / Plugins Required:

WebSocketNetworking (required)

GameplayAbilities (optional; GAS capabilities; compiled out when absent)

Niagara (optional; Niagara capabilities; compiled out when absent)

StateTree / ModelViewViewModel (optional; UE 5.5+ only)

UnLua (optional; Lua runtime capabilities)

Enhanced Input, Control Rig, MetaSound, PCG, etc. (optional; auto-gated at compile time when engine plugins are present)

Documentation: https://github.com/bytepine/NexusLink/blob/master/README.en.md

(Full docs: docs/usage-guide.md, docs/architecture.md, docs/tool-reference.md in the same repo)

Example Project: https://github.com/bytepine/NexusUnreal

(ThirdPerson sample + UnLua + MCP e2e tests. NexusLink is a git submodule, not bundled. Clone with --recurse-submodules or install the plugin separately.)

Important/Additional Notes:

Editor-only plugin; no gameplay/runtime classes are added to a packaged build. The MCP server is disabled by default; enable it under Edit > Editor Preferences > Plugins > NexusLink > Enable MCP Server.

Optional capabilities (GAS, Niagara, StateTree, MVVM, Lua, Enhanced Input, Control Rig, MetaSound, PCG, etc.) register only when their corresponding engine plugins are present in the project, so the plugin builds and runs cleanly without them.

For daily use, an IDE proxy (NexusRider, NexusVSCode, NexusDesktop) is recommended for instance discovery and long-lived WebSocket connections; direct HTTP to http://127.0.0.1:45000/stream is also supported.