Swallowtail automates Godot from your terminal, your scripts, and any tool you connect. It works against the editor you already have open: inspect and edit scenes, validate scenes and scripts, play the game, send input, read state back, capture frames, break and step in the debugger, then fix and verify without leaving the interface.

What is in the box

• An editor addon that hosts two local servers: a WebSocket server the swallowtail command line tool connects to, and an optional streamable-HTTP MCP endpoint an MCP client connects to with no extra process.
• Project-local commands. Drop a GDScript file in res://mcp_commands/ and it registers beside the built-ins, in the CLI, in help, and as an MCP tool.
• Undo where it counts. Supported scene edits go through the editor's undo history. Script and file changes are yours to review in version control.

No agent, model, or AI account is required. MCP is one optional interface.

Get the command line tool

The CLI and the agent skill are separate downloads from the releases page. The quickstart builds and plays a scene from an empty project.

Versions

Godot 4.7 is the target. 4.3 through 4.8 work in beta: a command group that needs a newer engine API is skipped and listed, never fatal.

Before you ship a game

The addon is development tooling. Disable the plugin and exclude addons/swallowtail/* in every export preset. Before you ship has the two steps and a scan of the pck that proves them.

Coming from godot-mcp

This addon shipped as Godot MCP/CLI on the Asset Library through 0.11. Existing projects move with swallowtail migrate. The migration page covers what changed and what stayed compatible.