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Hera Agent Godot lets AI coding agents inspect and control a live Godot editor in real time — instead of guessing scene structure from stale training data, the agent acts on the real editor and checks the result. Verified on every stable from Godot 4.2 to 4.7.

This Asset Library entry is the editor addon (the in-editor bridge). The companion hera CLI lives on GitHub and is what the agent actually runs.

Why a CLI, not MCP?

Godot already has a healthy MCP-addon ecosystem — Hera makes the opposite bet on purpose. MCP servers pay for breadth in tokens: dozens to 100+ tool schemas plus verbose JSON responses sit in the agent's context every turn.

Hera delivers MCP-grade reach over the live editor as a compact-JSON-by-default CLI — one command per action, minimal tokens, and it works with anything that can run a shell command (pipes, batch, CI, any agent), not just MCP clients. The agent loads zero tool schemas: the only resident surface is one small cacheable doc (~1k tokens) that stays flat no matter how many commands exist, versus an estimated ~4k–31k resident tokens for sampled Godot MCP servers.

What the agent can do

  • Read the editor — live status, scene tree, node property dumps, open scenes, editor selection, and ClassDB inspection.
  • Edit the scene — add / set / remove nodes, attach & detach scripts, wire resources, connect & disconnect signals. Every write is a single undoable step (Ctrl+Z).
  • Scripts & project — create scripts, make folders, list and scan project files, inspect and refresh resources and UIDs.
  • Run GDScript — evaluate an expression against the edited scene through an EditorInterface proxy.
  • Drive a running game — inspect and mutate the runtime tree, call helper methods, click controls semantically, inject real input and prove what was delivered, read the runtime UI tree, and assert on state.
  • Proof-first QA — capture and analyze screenshots, run requirement-covered QA scenarios from a file, and get a one-shot runtime health verdict with game qa diagnose.
  • Diagnostics — tail the Godot log with error/warning filters and summarize problems.

New in v0.9.0 — reach, and clearer feedback

  • Value-syntax hints in errors. When a node set, game node set, or resource set value can't be parsed, the error now names the exact Godot variant text to use — e.g. Vector2(x, y), a flat PackedVector2Array(x1, y1, x2, y2, …), Color(r, g, b, a), or node set-resource for object/resource properties — instead of failing without guidance. Agents recover in one turn instead of guessing.
  • Steadier game-QA lifecycle. game qa run/stop steps now confirm the runtime actually started or stopped (and the game instance cleared) before moving on, bound wait durations, and compare numeric eq/ne assertions numerically rather than as strings — so the run → inspect → QA → stop flow is reliable, including under CI.
  • Agent-side install. Get the hera CLI from the hera-godot npm package, a Homebrew tap, or an in-repo Scoop bucket, in addition to the one-line installers.
  • Agent harness kits. Drop Hera into a coding agent with the Claude Code plugin and the Codex plugin — both sharing one auto-invoked, ~1k-token live-editor skill — plus a Cursor rule template and a copy-paste AGENTS.md snippet.
  • Copyable nonvisual CI tier. A pinned Godot 4.7 headless lifecycle (enabled editor → smoke → game qa runtime logic) plus a static 4.2/4.7 script gate, documented so you can run the same verification on your own fork.

Command surface

status, instances, run / stop, scene, editor, script, project, classdb, node (read + write + resource/script wiring), signal, resource, game (runtime inspect + input + input-log + set/call/click + assert + QA + screenshot), guidance, game_feel, output, diagnostics, eval, screenshot, batch, and smoke — with --json (pretty) and --ids (paths only) output modes plus --instance and --timeout global flags; compact JSON is the default.

How it works

The addon is an @tool EditorPlugin that runs a localhost HTTP server and advertises the editor to the CLI via ~/.hera-agent-godot/instances/. The Go CLI discovers the editor and sends one compact JSON request per command, executed on the editor main thread through EditorInterface. No cloud and no account — everything stays on localhost, optionally behind the shared token.

Install

  1. Use any Godot 4.2–4.7 stable build (4.7 recommended — it gets the full QA treatment; see docs/SUPPORT_MATRIX.md in the repo).
  2. Copy hera_agent_godot/ into your project's res://addons/.
  3. Enable Project → Project Settings → Plugins → Hera Agent Godot.
  4. Grab the hera CLI from GitHub (one-line installer, npm, brew, scoop, or go build) and start driving the editor from your agent.

License

MIT-licensed. Source, output contract, support matrix, agent plugins, and the measured low-token methodology

Repo

If Hera saves your agent tokens, a star helps other Godot devs find it 🌟 github.com/NotNull92/hera-agent-godot

Links

Changelog for version v0.9.0

No changelog provided for this version.

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