How do I install the Sandbox skill?

Run npx skillmds@latest add tomevault-io/sandbox in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

What does the Sandbox skill do?

Visual HTML canvas sandbox for agent-driven UI and live previews Use when this capability is needed. It is listed under Web & Frontend on SkillMD.

Is Sandbox safe to use?

This skill has not completed SkillMD's automated safety review yet. Independent scanners report: SkillSpector: PASS, Skill Scanner: PASS. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Sandbox?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Sandbox free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Sandbox?

tomevault-io (@tomevault-io) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Sandbox by tomevault-io — Agent Skill

Name: Sandbox
Author: tomevault-io

File contents

Sandbox - Visual Canvas

Push HTML content to a live-updating canvas server for visual previews, dashboards, and agent-driven UI.

Commands

/sandbox start        - Start the canvas server (returns URL)
/sandbox push <html>  - Push HTML content to the canvas
/sandbox reset        - Reset canvas to blank state
/sandbox screenshot   - Take a screenshot of the current canvas
/sandbox status       - Show canvas server status and settings

Environment Variables

Variable	Description
`CANVAS_ALLOW_JS_EVAL`	Enable JavaScript evaluation in canvas (default: `false`)
`ALLOW_UNSAFE_SANDBOX`	Enable unsafe sandbox mode (default: `false`)

Examples

/sandbox start
/sandbox push <h1>Hello World</h1><p>Live preview</p>
/sandbox screenshot
/sandbox status
/sandbox reset

How It Works

/sandbox start launches a local HTTP server that serves the canvas page
/sandbox push <html> sends HTML to the canvas, rendered in real time
/sandbox screenshot captures the current canvas state as an image
/sandbox reset clears all HTML, CSS, and JS from the canvas
/sandbox status shows whether the server is running, the URL, and content sizes

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Frequently asked questions

Sandbox