Summer CLI skill for AI agents

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When your agent uses it

• The session has no summer_* MCP tools, or Summer was set up with summer setup <agent> —cli
• Running a Summer operation, a generation or an engine change from a shell, a script or CI
• A skill names an MCP tool or an operation and you need the summer command that runs it

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Install

npx -y summer-engine@latest skills install summer-cli --agent claude-code

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The skill

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The five commands in a game project

1. summer run . opens the project in Summer Engine. An agent’s run stays in the background.
2. summer engine get-project-context (MCP: summer_get_project_context) reads the project, its main scene and the engine version. Run it first.
3. summer engine play, then summer engine get-diagnostics (MCP: summer_play, summer_get_diagnostics), runs the game and reads its errors. summer engine stop (summer_stop) ends it.
4. summer engine screenshot (MCP: summer_screenshot) saves an image of the editor or the running game. Open its localPath to look.
5. summer ops search "<what you want>" (MCP: summer_search) finds any other operation. Run it as summer <area> <action> (MCP: summer_call), with --dry-run first for a change.

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1. Sign in once

summer login     # opens the browser: the Summer account, then the store and cloud operations
summer whoami    # who is signed in, and their credits

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2. Find the operation

summer ops search "make a sound effect"       # the best matches: name, effect, title
summer ops describe assets.generate_audio     # the exact input: fields, types, which are required

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3. Run it

summer assets generate-image --dry-run --prompt "a cozy pixel-art tavern" --aspect-ratio 16:9
summer engine set-prop --scene-path res://main.tscn --path Player --key position --value "Vector3(0, 1, 0)"
summer store status --game-id <id> --json

• Actions and fields are kebab-case: aspectRatio is --aspect-ratio, look_at is --look-at.
• --<field> alone sets a boolean field to true; --no-<field> sets it to false. Repeat a flag to give a list.
• Objects, and anything hard to quote, go in --input '<json>'. A flag wins over the same key in --input.
• --dry-run checks the input and changes nothing. For a spend it shows the estimate in credits. Put it right after the action: after summer setup <agent> --cli --allow-rules --yes (run that only when the person asks for it), Claude Code and Codex run it without asking (and the reads). Before each generation or other spend: dry-run it, tell the person what you will make, and wait for a yes.
• --idempotency-key <key> makes a retry safe: Summer runs a change once per key.
• --json prints only the answer: {"ok":true,"status":"done","result":{...}}. The exit code is 0 for every ok answer and 1 for an error.

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4. Long jobs

summer assets generate-3d --prompt "a wooden barrel" --wait          # runs, then follows the job to the end
summer jobs wait --job-id <id> --timeout-seconds 50                  # run it again until finished is true

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5. Approvals

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6. Files

• --out <folder or file> on a generate command, on summer jobs wait or on summer assets get saves the file there. In a Godot project, res:// paths work. The answer adds localPath.
• Without --out, a generation run inside a game project saves into its asset folder: Godot assets/, Unity Assets/Summer, Unreal Content/Summer, three.js public/assets. Outside a project, give --out.
• summer assets get --asset-id <id> saves only with --out.
• A save never overwrites a file. Tell the person the localPath.

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7. The engine

summer status                                              # is the engine up, and the sign-in
summer run ./my-game                                       # opens the project; for an agent, in the background
summer engine get-project-context                          # first call: project, main scene, engine version
summer engine get-scene-tree --scene-path res://main.tscn --depth 2
summer engine screenshot                                   # the answer's localPath is an image: open it to look

• Values are engine value strings, not JSON: "Vector3(0, 10, 0)", "Color(1, 0.5, 0, 1)". A resource is its class name: "BoxMesh".
• Name the scene in every change: --scene-path res://<scene>.tscn.
• 3 or more scene edits are one script, not a chain of commands. Write a func run(ctx): that ends with ctx.save_scene() to a file, then run summer engine run-script --scene-path res://main.tscn --source "$(cat build.gd)". The scene-scripting skill has the script API.
• With more than one editor open, set SUMMER_ENGINE_PROJECT to the project folder so the command picks the right one.
• summer tool <slug> --args '<json>' runs an engine tool by its 3.x name too. summer tool --list lists them.

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Without Summer Engine

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8. Errors

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Done means

• You ran each command and read its answer. Do not report an answer you did not get.
• Every spend had a dry run and a yes from the person first.
• Every file you made is saved, and you told the person its localPath.

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Related skills

• using-summer: Session bootstrap: how to find and use Summer skills and the summer-engine MCP before any response.
• summer-assets: Make game assets with Summer, no Summer Engine: find, generate and download 3D models, images, audio and video for any engine or app.
• scene-scripting: Build scenes, levels, HUDs and wiring with one editor GDScript (summer_run_script) instead of call chains.