rbx-studio-mcp

Free, open-source MCP server for Roblox Studio. Push-based SSE transport, editor-safe script edits, 29 token-lean tools.

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Roblox Studio MCP

MCP server for Roblox Studio: 29 tools over a push-based bridge, batched writes that undo as one step, editor-safe script edits. MIT.

The Studio MCP panel, showing calls and their latency

Install

1. The Studio plugin

npx -y @el4cteo/rbx-studio-mcp --install-plugin

Or download StudioMCP.rbxmx from Releases into your Studio plugins folder.

2. The server, in whichever client you use:

Claude Code

claude mcp add roblox-studio -- npx -y @el4cteo/rbx-studio-mcp

Codex CLI

codex mcp add roblox-studio -- npx -y @el4cteo/rbx-studio-mcp

Cursor — ~/.cursor/mcp.json or .cursor/mcp.json

{
  "mcpServers": {
    "roblox-studio": {
      "command": "npx",
      "args": ["-y", "@el4cteo/rbx-studio-mcp"]
    }
  }
}

Claude Desktop — claude_desktop_config.json

{
  "mcpServers": {
    "roblox-studio": {
      "command": "npx",
      "args": ["-y", "@el4cteo/rbx-studio-mcp"]
    }
  }
}

Gemini CLI — ~/.gemini/settings.json

{
  "mcpServers": {
    "roblox-studio": {
      "command": "npx",
      "args": ["-y", "@el4cteo/rbx-studio-mcp"]
    }
  }
}

Windsurf — ~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "roblox-studio": {
      "command": "npx",
      "args": ["-y", "@el4cteo/rbx-studio-mcp"]
    }
  }
}

VS Code / Copilot — .vscode/mcp.json

{
  "servers": {
    "roblox-studio": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@el4cteo/rbx-studio-mcp"]
    }
  }
}

opencode — opencode.json

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "roblox-studio": {
      "type": "local",
      "command": ["npx", "-y", "@el4cteo/rbx-studio-mcp"],
      "enabled": true
    }
  }
}

3. Open Studio and accept the 127.0.0.1 prompt — the plugin connects automatically. Verify with studio_status.

4. debug additionally needs Debugger Luau API in File → Beta Features, plus a Studio restart. Nothing else requires it.

The Debugger Luau API beta feature toggle in Studio

Port defaults to 44755 — change with --port or ROBLOX_STUDIO_MCP_PORT, and match it in the plugin widget. Loopback only.

Multiple agents

Register the server in as many clients as you like — the plugin connects out to one port, the first server owns it and the rest proxy through. No configuration, no second Studio connection.

Each agent keeps its own target (set_active_studio is per client), so two agents can work on two open places and neither can retarget the other. Pass studioId on a single call to reach elsewhere without changing your default.

Subagents share their parent's connection and therefore its target — a subagent calling set_active_studio silently retargets its parent. Give subagents an explicit studioId per call.

Tools


Session	`studio_status` `list_studios` `set_active_studio`
Discover	`tree` `inspect` `find` `api`
Scripts	`script_read` `script_edit` `script_grep` `script_create`
Instances	`create` `modify` `delete` `move`
World	`geometry` `assets` `collision` `undo`
Run & debug	`playtest` `execute_luau` `character` `input` `console` `debug` `performance`
Look	`screenshot` `viewport` `device`

Gotchas: during a playtest two sessions connect — pass studioId explicitly and use the edit session for anything that must persist. device emulation persists until device op="stop".

Batching

Every write tool takes an array — ten script edits or two hundred deletions is one call.

tool	takes	cap
`create`	instances, each nesting `children` to any depth	100
`modify`	entries, each with an unlimited list of `paths`	100 entries
`delete`	paths	200
`move`	moves	200
`script_edit`	edits, across any number of scripts	50
`script_create`	scripts	50
`inspect`	paths	50
`input`	input steps, delivered in order	40

modify caps entries, not targets — one entry can anchor five hundred parts, so pair it with find to change a whole place in one call.

Each batch is a single ChangeHistoryService recording: one Ctrl+Z. Batches are all-or-nothing — everything is transformed in memory first, so a failed match leaves the place untouched.

Parallel tool calls also work (responses are keyed by request id), but prefer a batch: N parallel calls are N round trips and N undo steps, a batch is one of each.

Compared to what else exists

	tools	transport	editor-safe writes	undo recording	live API dump	licence
this	29	SSE push	yes	yes	yes	MIT
Roblox built-in	~27	stdio	partial	—	n/a	closed source
Chrrxs	~40	poll	no	partial	no	MIT
drgost1	51	poll 500 ms	no	yes	no	MIT
boshyxd	43	long-poll	no	no	no	MIT (archived)
Roblox/studio-rust-mcp-server	2	HTTP	no	no	no	MIT (superseded)

Push, not poll — 50 sequential round trips: 13.6 ms mean vs 25.8 ms, 12.8 ms median vs 29.9 ms (node scripts/latency.mjs --count 50 --compare).
Safe script edits — ScriptEditorService:UpdateSourceAsync, not script.Source; your unsaved editor buffer survives.
~16k tokens of schema against 43–51 tools elsewhere. Cursor-paged, capped, detail: concise | standard | full.
Live API dump — property typos get suggestions (Anchorred → Anchored).

Not built here: terrain, AI mesh and material generation.

Security

Binds 127.0.0.1, rejects Origin, and requires a header a browser cannot set cross-origin — closing the DNS-rebinding hole. HTTP permission is granted per plugin and per URL, so your experience's "Allow HTTP Requests" setting is untouched.

Development

npm install
npm run build          # TypeScript -> dist/
npm run build:plugin   # plugin/src -> build/StudioMCP.rbxmx
npm run install:plugin # build + copy into the Studio plugins folder
npm test               # plugin (Luau) + bridge (Node) tests

Needs luau, luau-compile and luau-analyze from the Luau releases on PATH or in tools/.

evals/ holds ten questions answerable only by driving a real Studio session — see evals/README.md.

Licence

MIT.