romcp

Official domain: romcp.dev. Website deployment is being prepared as part of the v3 launch.

The programmable development and operations toolkit for Roblox Studio

romcp is the new name for Dominus. Version 3 retains the dominus-cli package name for upgrade compatibility and provides romcp, romcp-mcp, and romcp-install-plugin commands alongside the existing aliases. See the branding transition.

romcp gives MCP hosts direct, typed access to Studio instances, scripts, UI, reflection, output, and tests. Tools with structured schemas and risk hints cover inspection, mutation, 3D building, UI fidelity, testing, and Roblox Open Cloud commerce.

Version 3 includes an opt-in local developer API and a typed SDK at dominus-cli/sdk. The HTTP API contract remains a preview. See the API quickstart for implemented endpoints and authentication, and the release notes for known limits.

MCP script operations also support place-scoped project source mappings, local/Studio conflict reporting, and omission of source already available in a matching local file.

Persistent build preferences let direct and procedural builds inherit material, color, anchoring, collision, and stud-surface choices per place.

Features

The v3 preview also includes native UI-to-code export for React Luau and plain Luau, with typed snapshots and explicit fidelity diagnostics.

• Typed tools with schemas: Input validation and structured results for every Studio operation
• Zero friction setup: Guided installer handles credentials, plugin installation, and MCP client detection
• Atomic mutations: Batches and UI replacements are undoable; changes roll back on failure
• Stable refs: Instance references survive renames, reparenting, and duplicate sibling names
• Parallel coordination: MCP-native Sampling for multi-agent Studio work with coordinator-owned writes
• Revision-locked scripts: Write protection via revision tokens from studio_read_script
• Dockable control panel: Live connection state, reconnects, Luau safety toggle, and project rules
• Optional code execution: Explicitly enabled and per-request confirmed Luau runs for custom builds
• 3D building utilities: Part creation, cloning, transforms, CSG unions, spatial queries, and procedural geometry
• Windows Studio capture: Non-focusing full-window screenshots and consistent multi-region crops without Studio screenshot permission
• Commerce APIs: Developer products and game passes via Roblox Open Cloud with duplicate checks
• Admin panel: Connection diagnostics, forced reconnects, target selection, and database inspection
• Secure bridge: Single background process, token auth, stdio transport, rate limits, and method allowlist

Requirements

• Node.js 20 or newer
• Roblox Studio with HTTP requests enabled for Studio/plugin use
• An MCP client such as Codex, Claude Code, Claude Desktop, Cursor, or VS Code
• A scoped Roblox Open Cloud API key when creating developer products or game passes
• A numeric Roblox creator user or group ID when uploading assets through Open Cloud

romcp does not require its own AI API key. Your MCP host supplies the model. Commerce creation reads ROBLOX_OPEN_CLOUD_API_KEY from the MCP server environment, or openCloudApiKey from romcp config. Grant only developer-product:read, developer-product:write, game-pass:read, and game-pass:write for the intended experience. Asset uploads use the same key with asset read/write access. Pass creatorGroupId to roblox_upload_asset for a group-owned upload or creatorUserId for a user-owned upload. Defaults can come from ROBLOX_CREATOR_GROUP_ID, ROBLOX_CREATOR_USER_ID, ROBLOX_USER_ID, robloxGroupId, or robloxUserId in romcp config. The API key must authorize the intended creator, including the target group for group-owned uploads.

Installation

pnpm install -g dominus-cli@latest

Run the guided setup:

dominus setup

This provisions your local credential, installs the Studio plugin, configures your MCP client, and verifies the connection. Roblox Studio reloads the plugin automatically.

For unattended setup: dominus setup --yes --skip-studio-check

Updating

dominus update

An explicit update always checks npm instead of relying on the passive update cache, upgrades through the package manager that installed romcp, and installs the matching Studio plugin. Current bridge versions are restarted gracefully so the new background code takes effect too. Reload Studio after it completes. When the local bridge discovers a newer release, the Studio plugin logs a warning and opens an update card once for that release.

Configuration

Add to your MCP client config:

{
  "mcpServers": {
    "dominus": {
      "command": "dominus-mcp"
    }
  }
}

For version-pinned setup without global install:

{
  "mcpServers": {
    "dominus": {
      "command": "pnpm",
      "args": ["dlx", "dominus-cli@latest", "dominus-mcp"]
    }
  }
}

Getting started

1. Run dominus setup to install the plugin and configure your client
2. Open Roblox Studio and start your MCP client
3. romcp authenticates automatically with no manual pairing

The romcp toolbar panel shows connection state, reconnect controls, Luau execution toggle, and project rules that sync with your MCP host.

Run dominus doctor --wait 30 to verify the plugin/bridge connection.

Tool patterns

Inspection & scripting: Read the tree, scripts, selection, and API docs. Script updates are revision-locked; use studio_read_script to get the revision token.

UI building: Use studio_build_ui then studio_snapshot_ui to compare fonts, UDim2 values, colors, and hierarchy. Take screenshots to verify layout.

Windows capture: studio_capture_window captures only the active romcp Roblox Studio window without focusing it or sending input. Request one full client/window image or up to 12 labeled pixel crops from the same frame. If Roblox's DirectX surface rejects native window capture, romcp copies visible pixels only after proving that no other application overlaps the target; otherwise it fails without taking a screenshot.

3D building: Batch create parts with studio_create_parts, clone templates with studio_clone_instances, transform with studio_transform_instances, and organize with grouping tools. Use studio_query_parts for spatial discovery and studio_union_parts for CSG. Verify with studio_review_3d.

Procedural geometry: studio_run_build_program combines lines, helixes, rings, grids, and spheres in one undoable operation. Specify tapered sizes and path-aware rotations for structures like spiral trees.

Code execution: studio_run_luau runs generated Luau (off by default; toggle with toolbar button). Requires confirm=true. Code should return or call dominus.track(model) so the tool captures and screenshots results.

Parallel work: run_parallel_task fans out to Sampling workers for independent subtasks. Workers are proposal-only; the coordinator validates and applies changes atomically.

Metadata: Use studio_get_metadata, studio_set_attributes, and studio_update_tags for instance data. romcp writes real Studio attributes/tags directly.

Commerce: roblox_create_developer_product and roblox_create_game_pass hit Open Cloud APIs with duplicate checks. Requires confirm=true. Never invents IDs.

Tool catalog

Connection tools:

• dominus_status
• dominus_select_studio

Parallel coordination:

• run_parallel_task

Studio inspection:

• studio_get_tree
• studio_inspect
• studio_get_selection
• studio_read_script
• studio_snapshot_ui
• studio_get_output
• studio_get_reflection
• studio_get_metadata
• studio_list_callable_methods
• studio_query_parts
• studio_review_3d
• studio_capture_window (Windows only; full Studio window or multi-region PNG crops)

Studio changes and verification:

• studio_update_script
• studio_apply
• studio_create_parts
• studio_clone_instances
• studio_transform_instances
• studio_group_instances
• studio_ungroup_instances
• studio_create_welds
• studio_union_parts
• studio_run_build_program
• studio_run_luau
• studio_set_selection
• studio_set_attributes
• studio_update_tags
• studio_invoke_methods
• studio_delete_instances
• studio_build_ui
• studio_run_test

Roblox documentation:

• roblox_search_api
• roblox_get_api

Roblox Open Cloud commerce:

• roblox_commerce_status
• roblox_list_developer_products
• roblox_create_developer_product
• roblox_list_game_passes
• roblox_create_game_pass

Roblox Open Cloud assets:

• roblox_upload_asset (user- or group-owned images, models, and audio; images can be applied to a Studio target)

Security

• Bridge: Local-only WebSocket on 127.0.0.1, token-authenticated, message-size limited, rate-limited
• Plugin: Shipped with placeholder credentials; setup writes the user-specific token to the local copy
• Commands: Explicit allowlist; reflected methods pass a capability policy (excludes destructive, network, signal operations)
• Luau execution: Opt-in toggle (default off) plus per-request confirmation
• Transport: stdio (MCP standard)

Development

pnpm install
pnpm lint
pnpm typecheck
pnpm test
pnpm build
pnpm build:plugin
npm pack --dry-run

The editable toolbar icons and Roblox-upload PNGs live in plugin/assets. Roblox toolbar icons require moderated asset URIs; upload both PNGs from the creator account and replace the temporary toolbar asset IDs before publishing the plugin.

Run the MCP server in development:

pnpm dev:mcp

The design and research notes are in docs/DOMINUS_2_PLAN.md.

License

Dominus License 1.0 — you may use romcp and modify your own copy, but you may not sell, redistribute, rebrand, or claim the software or a modified version as entirely your own. This is not an open-source license.