Let an agent animate (MCP)

The OpenBone MCP server gives an AI agent the same operations the editor uses: every edit is a tool (add_bone, set_keys, add_state, add_listener…), plus tools to check its own work (rendered frames, GIFs, state-machine simulations, pose inspection) and to export. Connect the editor to the server and you watch the agent’s edits arrive live, and can edit alongside it.

WindsweptClick the buttons on the left of the artworklive

Play with sound

talkgullsgustmusicOfffxOff

Windswept was built this way: an AI agent made it with the OpenBone MCP server, from the physics hair and the mesh grass to the lip-synced lines, the buttons and the mixer.

Connect a client

1. Add the server to your MCP client.

   Claude Code

   Inside a checkout of the repository there is nothing to do: it ships .mcp.json, so Claude Code starts the openbone server automatically. Anywhere else:

   claude mcp add openbone -- npx -y @openbone/mcp

   Other clients

   Most clients (Claude Desktop, Cursor, VS Code…) take a JSON entry like this:

   { "mcpServers": { "openbone": { "command": "npx", "args": ["-y", "@openbone/mcp"] } } }

   From a checkout

   { "mcpServers": { "openbone": { "command": "pnpm", "args": ["exec", "tsx", "/path/to/OpenBone/packages/mcp/src/bin.ts"] } } }

   HTTP

   npx -y @openbone/mcp --http 7718    # streamable HTTP at http://127.0.0.1:7718/mcp

2. Open the editor and click ⚡ Connect MCP in the toolbar. The editor connects to the server’s live bridge (ws://127.0.0.1:7717), loads the server’s document, and the button turns into ● Live MCP.

3. Ask the agent for something:

   Create a project at ~/anim/robot.obone: a robot with IK arms, an idle and a wave animation, and a state machine that waves when clicked.

Live: the agent created the wave animation and set the head and antenna keys with set_keys; the editor shows them as they arrive.

What the agent can do

Group	Tools
Project	new_project, open_project, save_project (projects with a path autosave), get_summary, get_document, validate, undo, redo, import_image, import_audio, get_guide
Art prep	process_image: remove a flat background, cut out what differs from a painted-out copy, trim, crop, resize, flip, feather edges
Editing	One tool per editing operation: bones, slots, regions, meshes, shapes, text, constraints, animations, keys, events, state machines, inputs, states, transitions, listeners, scripts, skins, atlases
Rigging helpers	trace_mesh, auto_weights, set_weights_in_area, smooth_weights, prune_weights, pose_bones, lip_sync
Audio	add_sound, add_bus, set_audio_mix, add_audio_key, set_event_sound, set_state_sound
Checking	render_frame (a PNG with bones and hit boxes), render_gif, simulate_state_machine, inspect_pose, get_stats
Export	export_file: every format the Export dialog has, MP4 and WebM with sound included, and pack_atlas

The MCP server reference lists every tool and option. Resources (openbone://guide, openbone://document, openbone://summary) and prompts (rig_character, interactive_button) give the agent a head start.

How live editing works

The server owns the document. When you connect, it sends its current document; after that both sides exchange ops: the agent’s tool calls arrive in the editor, and your own edits in the editor go to the server, so the agent sees them on its next read. Undo and redo in the editor are forwarded to the server. If an op fails, the editor is resynced from the server’s copy.

Tip

Agents work best when they check their work. Ask for a render_frame after rigging and a simulate_state_machine run after wiring inputs; both are cheap, and they catch a bone rotated the wrong way before you do.

Running the server

Command	What it does
npx -y @openbone/mcp	stdio server, plus the live bridge on ws://127.0.0.1:7717
… --project ~/anim/hero.obone	opens (or creates) a project at startup
… --http 7718	streamable HTTP at http://127.0.0.1:7718/mcp
… --bridge-port 7800	the live bridge on another port
… --no-bridge	no WebSocket bridge

The CLI starts the same server with openbone mcp.