s&box

MCP Server

In-editor MCP server for s&box — drive the editor in natural language with Claude Code (or any MCP client). Editor open = MCP up, close = gone. No subprocess, no WebSocket bridge, no reconnect dance.

What it can do (48 tools)

Scene graph (12) — scene_list_objects, scene_get_object, scene_create_object, scene_delete_object, scene_clone_object, scene_reparent_object, scene_set_transform, scene_get_hierarchy, scene_load, scene_find_objects (wildcards), scene_find_by_component,

scene_find_by_tag

Components (5) — component_list, component_get, component_set (typed: Model, Material, Color, Vector3, Angles, cloud-asset idents), component_add,

component_remove

Tags (3) — tag_add, tag_remove,

tag_list

Cloud assets (4) — asset_search (s&box library), asset_fetch, asset_mount (auto-pins into .sbproj PackageReferences),

asset_browse_local

Editor (11) — editor_get_selection, editor_select_object, editor_undo/editor_redo, editor_save_scene, editor_take_screenshot (CameraComponent → PNG), editor_play/editor_stop/editor_is_playing, editor_scene_info,

editor_console_output

Files & execution (7) — file_read, file_write (.cs → code/, else Assets/), file_list (glob), project_info, console_run, execute_csharp (Roslyn scripting when available),

get_server_status

Docs & API search (6) — built-in crawler over docs.facepunch.com (180+ pages) and the Facepunch API schema (1,800+ types):

sbox_search_docs (fuzzy search, optional category filter)
sbox_get_doc_page (Markdown, chunked output)
sbox_list_doc_categories
sbox_search_api (types + members)
sbox_get_api_type (full type details — methods, properties, fields, XML docs)
sbox_cache_status

Features under the hood

HTTP/SSE transport on localhost:29015 — no external processes
Reflection-based tool discovery via [McpToolGroup] + [McpTool] attributes — new tool = new method with an attribute
Main-thread dispatch — all editor-API calls land safely on the editor's main thread (no Qt crash)
Dirty tracking via FullUndoSnapshot + OnEdited + reflection setters — close-without-save prompt works
Process singleton — survives hot-reloads, no bind-conflict loop
Dock UI with live status, request counter, uptime, activity log
Graceful degradation — Roslyn-scripting fallback, multi-stage schema-URL resolver, doc-crawl cold-start retry

Setup in 30 seconds

Clone the repo
s&box: File → Open Project → src/SboxMcp/.sbproj
claude mcp add --transport http -s user sbox http://localhost:29015/mcp
Done — Claude sees all 48 tools

Architecture

Claude / MCP client  ── HTTP :29015 ──>  s&box editor
                                          ├── McpHttpServer (HttpListener)
                                          ├── ToolRegistry (reflection)
                                          ├── HandlerDispatcher (main-thread)
                                          ├── Handlers/ (editor APIs)
                                          └── DocsService (crawler + fuzzy index)

One process. 48 tools. Direct access to every editor API. Ask Claude what you want.

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