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.

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

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

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

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

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

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

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

{
  "$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.

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

Related MCP server: Roblox Studio MCP

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

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.

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

• 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.