Loopcut MCP server

loopcut

The connector for Loopcut, an open-source AI agent inside Blender: cloud render, assets, images, 3D models, motion and audio for Claude Code, Codex, Cursor, Claude Desktop and the shell, and as a hosted connector for claude.ai and ChatGPT. Render .blend files on cloud RTX 4090s, search free asset libraries, make and edit images, turn images into 3D models, remesh meshes, rig characters, make sound effects and voice lines, and turn a video or a sentence into character animation on your own rig. Results come back as files the agent imports with Blender's Python. Everything is paid from your Loopcut account's credits. You don't need the Loopcut app; any Blender install packs the scene.

It's one MCP server plus a CLI with the same verbs. The tools come from Loopcut's catalog, so a cloud tool that opens on Loopcut shows up without a new release.

Tool	What it does	Result
loopcut_login	Signs in or switches account. Any tool does it by itself the first time: a browser opens, you approve, and the call carries on
loopcut_account	Plan, credit balance, Private mode and no-generation settings, and which tools you can use
render_quote	Packs the saved scene with headless Blender, uploads what the cloud lacks and prices the render	PNG frames and a QA report
asset_search	Searches Poly Haven, ambientCG and Physically Based. Free, and it runs at once	Matches with licence and download details
image_generate	Makes an image from a prompt, optionally guided by a reference image: concept art, backplates, textures (transparent background on request)	PNG
image_edit	Changes an existing image from an instruction, with an optional mask: a paint-over or restyle of a render	PNG
image_to_3d	Makes a textured model from a prompt, an image or both	GLB
remesh	Rebuilds a GLB mesh with clean quads or triangles and bakes its textures onto it	FBX (quads) or GLB (triangles)
auto_rig	Rigs a humanoid character in a saved .blend: a skeleton with Mixamo bone names and skin weights on the original meshes. Your Blender checks it first for free; the finished job binds the rig and saves the file	the rigged .blend
sound_effect	Makes a sound effect from a description	WAV
voice_line	Speaks a line with a chosen voice and direction	WAV
job_start	Starts a quoted job, which spends credits. Calling it again returns the same job
job_status	Waits for a job, or up to 10 at once (job_ids), and downloads the results, hash-checked and resumable. Running jobs say about how long is left
job_cancel	Cancels a job and refunds unspent credits

Results are files the next tool takes: a generated image as image_to_3d's image, a model as remesh's model, a rendered frame as image_edit's image. With a budget from you, the agent passes max_credits to a paid tool, which starts a quote within it at once instead of returning it for job_start.

A character from a photo, rigged and animated: image_edit the photo into a T-pose with separated fingers, image_to_3d from that with topology: "quads", import it and save the .blend, auto_rig it (20 credits), then motion_from_text and motion_apply. auto_rig takes humanoids with clear arms, legs and fingers, up to 100,000 triangles; a rig that can't be bound is refunded automatically.

Motion

Two motion tools, with a free local tool to use their results:

Tool	What it does	Price	Result
motion_from_video	Captures a person's whole-body motion, hands included, from a local MP4, MOV or WebM (NVIDIA GEM-X). One person, whole body in view, a mostly still camera; at most 60 s per job, chosen with start_s and end_s, from a file up to 200 MB	3 credits per second captured, 2-second minimum	motion.bvh + motion.json
motion_from_text	Makes 2–10 s of body animation from a description of one simple physical action (NVIDIA Kimodo, Built with Meta Llama 3). Good at grounded motion (walks, dances, kicks, gestures, fighting in place); flips, spins in the air and big jumps come out small or missing. The fingers stay still; it isn't for faces, props or finger work	2 credits per second of motion	motion.bvh + motion.json
motion_apply	Retargets a result onto the humanoid rig in a saved .blend with your Blender, headless, and saves the file. Mixamo, Rigify, Auto-Rig Pro, Unreal mannequin, or any humanoid by bone names; with no rig, SOMA's own skeleton with a simple body. Free and local	free	the animated .blend

motion.bvh is a rig-neutral SOMA 77-joint skeleton (standing T-pose rest, centimetres, Y up, 30 fps). The connector measures the clip's length itself (MP4 and MOV from the file header, WebM with ffprobe when it's installed) because the quote holds the seconds captured. target_armature and in_place on a motion tool are kept on your machine for motion_apply and never sent to Loopcut. job_status returns the result with three ways to use it: motion_apply (or loopcut motion-apply) for a saved .blend, a short Python snippet for a Blender that's already open (for example through another Blender MCP), and Blender's plain BVH import. The retargeting is the Loopcut add-on's own, so results match the app. With no-generation on, motion_from_video stays available (it records the user's own performance) and motion_from_text is hidden.

Price. 1 credit = $0.01. Every paid tool quotes first, for free, and the quote is the most a job can cost. Rendering costs 5 credits per GPU-minute on an RTX 4090 with a one-minute minimum; the other prices are on loopcut.org/pricing. Asset search, quotes, packing and the render QA report are free. Failed jobs are refunded. New accounts start with 100 credits.

Install

You need uv (it provides Python 3.10+), and Blender if you render or apply a motion. To get uv: brew install uv or curl -LsSf https://astral.sh/uv/install.sh | sh on macOS and Linux, powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex" on Windows.

claude.ai, ChatGPT and Claude Desktop, nothing to install: add https://loopcut.org/mcp as a connector and sign in with Loopcut. In Claude: Customize → Connectors → Add custom connector. In ChatGPT: chatgpt.com/plugins → + → Add custom MCP server (custom servers with paid tools need a Business, Enterprise or Edu workspace until Loopcut is in ChatGPT's plugin directory). The hosted connector has asset search, images, 3D models, remeshing, motion from text, sound, voice and rendering from a script, and returns download links; one tool's result feeds the next by its job:<job_id>/<name> ref. Rendering your own .blend and motion from a video need the plugin below, because they read files on your computer.

Claude Code (plugin, which includes a skill that teaches the agent the tools and the habits that save credits)

/plugin install loopcut --marketplace loopcut-ai/loopcut

On Claude Code before 2.1.275, run /plugin marketplace add loopcut-ai/loopcut and then /plugin install loopcut@loopcut. Or add only the MCP server:

claude mcp add loopcut -- uvx loopcut mcp

Codex (plugin, with the same skill)

codex plugin marketplace add loopcut-ai/loopcut
codex plugin add loopcut@loopcut

Or add only the MCP server:

codex mcp add loopcut -- uvx loopcut mcp

Every tool call returns within 50 s, under Codex's default 60 s tool timeout; long work carries on between calls. Both plugins start the server with uvx loopcut==<release> mcp, pinned to the release they ship with; the package has no dependencies beyond Python.

Cursor, VS Code, Claude Desktop and other MCP clients

{
  "mcpServers": {
    "loopcut": {
      "command": "uvx",
      "args": ["loopcut", "mcp"]
    }
  }
}

Apps opened from the Dock or Start menu may not see your shell's PATH. If the server doesn't start, use the full path from which uvx as command.

The first call opens a browser to sign in, and the key is kept where only you can read it. Without a browser (over SSH, say), the call returns the link for you to open. LOOPCUT_API_KEY skips all of this.

CLI

loopcut login                                         # once per machine
loopcut account                                       # plan, credits, settings
loopcut tools                                         # the open tools and their inputs
loopcut render shot.blend --frames 1-120 --samples 256 --max-credits 300
loopcut run asset_search --input '{"query": "oak floor", "kind": "material"}'
loopcut run image_to_3d --input '{"prompt": "a brass desk lamp", "quality": "draft"}' --file image=lamp.png --max-credits 30
loopcut quote sound_effect --input '{"prompt": "a heavy wooden door slams", "duration_seconds": 2}'
loopcut run motion_from_video --file video=take.mp4 --input '{"static_camera": true}' --blend shot.blend --max-credits 60
loopcut run motion_from_text --input '{"prompt": "a person jumps over a puddle", "duration_s": 4}' --yes
loopcut motion-apply --blend shot.blend --bvh loopcut_outputs/JOB_ID/motion.bvh --armature Hero --in-place
loopcut motion-apply --bvh loopcut_outputs/JOB_ID --bpy        # Python for a Blender that's already open
loopcut start QUOTE_ID | status JOB_ID --wait | fetch JOB_ID --out DIR | cancel JOB_ID
loopcut settings --private-mode off                   # or on; also --no-generation on|off

Install the command with uv tool install loopcut, or run any command without installing as uvx loopcut …. run and render quote, then start only with --yes, under --max-credits N, or after you answer the prompt. run of a motion tool with --blend also puts the motion on that scene's rig; motion-apply saves over --blend (Blender keeps the previous file as .blend1) unless you give --out. Results print as JSON on stdout; progress goes to stderr. In CI, create a key on loopcut.org/account and set LOOPCUT_API_KEY.

Settings

Variable	Meaning
LOOPCUT_API_KEY	A Loopcut key (lc_…) to use instead of the stored sign-in, e.g. in CI
LOOPCUT_BLENDER	The Blender executable used for packing and for motion_apply. Without it, the tool checks BLENDER, then PATH, then the usual install folders
LOOPCUT_SERVICE_URL	The service, https://loopcut.org by default
LOOPCUT_CONNECTOR_HOME	Where the sign-in, quotes, jobs and the last tool catalog are kept. Default: ~/.config/loopcut-connector, or %APPDATA%\loopcut-connector on Windows. It is separate from the Loopcut app's own files

Private mode and no-generation. These account settings apply here too. Private mode (on by default on paid plans) refuses tools whose provider may train on what it receives; today that is sound effects. No-generation hides and refuses the generative tools. Change them in the Loopcut app or with loopcut settings.

How it works

1. Quote. Every tool goes through the same job API the Loopcut add-on uses. A quote prices the exact request and lasts ten minutes; an expired one is renewed at start, and the job goes ahead only if the price didn't change. Starting the same quote twice returns the same job.
2. Files in. File inputs are local paths. They're checked (type and size), addressed by SHA-256, and only uploaded if the cloud doesn't already have them, straight to storage with presigned URLs. Big files go in parts, each retried on its own.
3. Render packing. A background Blender (-b --factory-startup --disable-autoexec) opens the saved .blend and runs the Loopcut add-on's own collector (addon/bundles.py, vendored). It copies every texture, library, cache and sequencer file into a bundle with relative paths. That Blender gets a private config folder and none of your environment's keys. The cloud never runs Python from your file, and the renderer has no internet access.
4. Files out. Results are checked against their hashes and saved into loopcut_renders/<job_id>/ next to the .blend for a render, and loopcut_outputs/<job_id>/ in the working folder for everything else (or out_dir). The working folder is the client's workspace root when it shares one; Codex starts plugin servers in the plugin's own folder, so there results go under your home folder instead. A render's QA report flags black, white, flat and transparent frames, fireflies, duplicate frames and exposure jumps.
5. Motion onto a rig. motion_apply starts the same kind of background Blender on your saved .blend and runs the add-on's retargeter (addon/motion_retarget.py, vendored) through loopcut/motion_blender.py: one whole-body rest alignment, limb-only direction alignment for A-pose rigs, the pelvis path scaled by leg length from the character's own standing height, and keys written parent first. A previous action on the rig is kept in a muted NLA track. Nothing leaves your machine and it costs nothing.
6. Rigging. auto_rig runs the add-on's rigging code (addon/autorig.py and rig_*.py, vendored) in a background Blender through loopcut/rig_blender.py, once on each side of the cloud job: first it checks the named meshes and writes the upload (the meshes as a GLB and a rig task with their fingerprints) to the state folder, without changing the .blend; after the job it checks the character is unchanged, verifies the returned skeleton and weights against what was sent, binds them to the original meshes and saves.

If the catalog can't be read at startup, the server uses the last catalog it read from that service, then the snapshot in src/loopcut/catalog.json.

What it runs and connects to. uv, which provides Python (and downloads it if needed); your Blender, headless, only to pack a scene for render_quote, to apply a motion with motion_apply and to check and bind a rig for auto_rig; ffprobe, if installed, only to measure a WebM clip; and your browser, only to open the Loopcut sign-in page. It connects to loopcut.org (the catalog, sign-in and job API) and to the presigned storage URLs that API hands out for uploads and downloads. It sends no analytics.

Privacy Policy

Loopcut's privacy policy is at loopcut.org/privacy. For this connector:

• What it sends. The Loopcut key on every request, with the client's name and version. For a render, the packed scene: the saved .blend and every texture, library and cache it uses. For other tools, the inputs you or the agent give (prompts, settings) and the files named as inputs (images, meshes, videos). It reads nothing else from your machine: no other files, no environment keys besides LOOPCUT_API_KEY, no open Blender session. motion_apply opens and saves the .blend you name on your machine only, and target_armature and in_place stay local too. For auto_rig it sends the named meshes (as a GLB) and their fingerprints, not the .blend, and binds the result on your machine.
• Where it's stored. Loopcut's database (Supabase, US) holds your account, quotes and jobs; uploaded files and results are kept in Cloudflare R2.
• Third parties. Each job goes only to the provider that runs it: today OpenAI, fal and the model developers it runs (Deemos for Rodin, Tripo), Google Cloud, ElevenLabs and RunPod. Providers' own retention terms are on the privacy page. Private mode, on by default for paid plans, refuses tools whose provider may train on what it receives (today, sound effects).
• Retention. Uploaded files are deleted 7 days after their last use and results 30 days after theirs. Account and billing records are kept while the account exists. Results you download are ordinary files on your machine.
• On your machine. The key, quotes, jobs and the last tool catalog are kept in ~/.config/loopcut-connector, readable only by you. loopcut logout removes the key.
• Contact. hello@loopcut.org, also for exporting or deleting your account data.

Development

PYTHONPATH=src python3 -m unittest discover -s tests       # MCP protocol and unit tests
LOOPCUT_TEST_BLENDER=/path/to/blender PYTHONPATH=src python3 -m unittest tests.test_blender_pack
python3 scripts/snapshot_catalog.py                         # refresh the fallback catalog before a release

The end-to-end tests run against Loopcut's contract mock, which lives in the service repository; they're skipped here. addon/VENDORED.md explains how the add-on copies are kept in sync.

Released under the GPL-3.0-or-later. Loopcut is an independent project; Blender is a trademark of the Blender Foundation.