MCP servers
MCP is the open standard that lets Claude and other AI agents use software. Four of our Mac apps include an MCP server, so your agent can work them on your Mac: Bias for TASCAM Model mixers, Yoke for the Universal Audio OX amp box, Rig for studio MIDI and audio, and Play for songwriting on your own instruments. Our open source tools ship servers of their own: Ruse for building audio plugins and Symbia for keeping a signed record of an agent's work. Every server accepts connections from your own Mac only, and none of them sends anything to us.
One design in four apps
If you're connecting an agent, the four app servers work the same way. Each speaks JSON-RPC 2.0 over HTTP POST on 127.0.0.1, one port per app. You turn it on or off under Settings › MCP, which also lists the tools called since the app opened. For clients that start a program, a relay inside each app bundle carries stdio to the server. The relay answers initialize with the app closed, and tool calls return an error until you open the app. Each server's apps tool asks the other three ports which apps are open.
| Server | Port | Tools | At launch |
|---|---|---|---|
| Bias | 4848 | 34, from status, strips and set_param to songs, markers, takes and the app's own ledger. Bias refuses insert changes while the recorder rolls unless the call says force | Off until turned on in Settings |
| Yoke | 4747 | 17, from front_panel and meters to set_control, set_insert, set_route, presets, configurations, venue and Wi-Fi. Every write returns the unit's readback | Off until turned on in Settings |
| Rig | 4850 | midi-mcp's 42, from list_devices and diagnose to add_route, save_snapshot, lock_sample_rate and the MIDI Express XT tools, on the same CoreMIDI client as the window | On |
| Play | 4849 | 36, from catalog_scan and probe to songs, parts, sounds, pads and performance_play | On |
| ruse-mcp | stdio | 12, to create, build, check, package and render plugins | Started by the client |
| symbia | stdio | 15. Nine for the ledger, record, seal, report, search, get, find, list, status and promote, and six for the host, exec, read, write, edit, job and open. Every call is recorded | Started by the client |
Connect Claude Code
With the app open, add it by name and port. For Bias:
claude mcp add --transport http bias http://127.0.0.1:4848/mcpIf your client starts a program, as the Claude desktop app does, point it at the relay inside the app bundle. Each relay is named for its app: bias-mcp, yoke-mcp, rig-mcp and play-mcp.
"mcpServers": { "bias": { "command": "/Applications/Bias.app/Contents/MacOS/bias-mcp" } }Symbia, installed with Homebrew:
brew install symbia-labs/tap/symbia
claude mcp add --scope user symbia -- /opt/homebrew/bin/symbia mcpRuse's getting-started guide covers Claude Code, the Claude desktop app, Codex, Gemini CLI, OpenCode, Cursor and VS Code. The Bias documentation lists every call the Bias server takes.