What is an agent kit?
Tested instructions for a coding agent, plus proof they work and a lesson on changing the result. Why that's a different product from a prompt, and from code.
An agent kit sells tested instructions for a coding agent. You don't get a zip of source code. You get the thing that produces the source code, and your agent writes it fresh, in your folder, on your machine.
That sounds like a prompt, and the builder prompt is the centre of it. But a kit has three parts, and the other two are what make it worth paying for.
The three parts
The builder. A prompt, or a SKILL.md with reference files, that makes Claude Code, Codex or Cursor build the whole thing from scratch. A good builder prompt is 600 to 1,200 words: the outcome, the constraints, and the data blocks named so you can point at them later. It can carry a few fixed files when the agent shouldn't improvise them (a Slack app manifest, a Web Store privacy template). The rule is: if the agent can build it reliably from instructions, ship instructions.
The demo. The real output of that builder, hosted as a page you can use, or a two-minute screen recording when the thing can't run in a browser (a Slack bot, a Mac menu bar app, a Chrome extension). The demo is proof. If you like what it does, you already know what you're buying.
The lesson. Five short steps, about ten minutes: run the prompt, read what it built, change the data block, add your own touch, publish it. The lesson is the "academy" part. It turns a one-off build into a skill you keep.
Why instructions instead of code
A template is code you have to edit. A kit is a build that adapts to what you ask for. "Make it about telling the time instead of fractions" is a sentence, not a refactor. The build also gets better as models get better, without the creator shipping a new version.
The honest downside: two runs are never byte-identical. That's why every kit on Robot Academy is run by a person in a clean agent session before it's listed, why kit pages say which tools they were tested with, and why there's a 14-day money-back window until you reveal the prompt.
What a kit is not
It's not an AGENTS.md file. Those are written for one specific repository, and your agent generates one in seconds. It's not a bare prompt with a screenshot. And it's not a course: the lesson is ten minutes because the point is to get you changing the thing, not watching someone else change it.
How to tell a good one
Three questions. Does the demo match the description? Does the lesson tell you where in the build to look, by name? Can you describe, in one sentence, the first thing you'd change? If the answer to all three is yes, you'll get your money's worth in the first evening.