Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/vercel-labs/json-render/reactnpx skills add vercel-labs/json-render --skill reactgit clone --depth 1 https://github.com/vercel-labs/json-renderWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00041 | $0.02667 |
| Opus 5 | $0.00020 | $0.01333 |
| Sonnet 5 | $0.00008 | $0.00533 |
| Haiku 4.5 | $0.00004 | $0.00267 |
Grade A, and why
react scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 299 lines — stays where its author put it; the contents beside it link to each section on GitHub.
@json-render/react
React renderer that converts JSON specs into React component trees.
Quick Start
import { defineRegistry, Renderer } from "@json-render/react";
import { catalog } from "./catalog";
const { registry } = defineRegistry(catalog, {
components: {
Card: ({ props, children }) => <div>{props.title}{children}</div>,
},
});
function App({ spec }) {
return <Renderer spec={spec} registry={registry} />;
}
Creating a Catalog
import { defineCatalog } from "@json-render/core";
import { schema } from "@json-render/react/schema";
import { defineRegistry } from "@json-render/react";
import { z } from "zod";
// Create catalog with props schemas
export const catalog = defineCatalog(schema, {
components: {
Button: {
props: z.object({
label: z.string(),
variant: z.enum(["primary", "secondary"]).nullable(),
}),
description: "Clickable button",
},
Card: {
props: z.object({ title: z.string() }),
slots: ["default"],
description: "Card container with title",
},
Layout: {
props: z.object({}),
slots: ["default", "header", "footer"],
description: "Layout with named content regions",
},
},
});
// Define component implementations with type-safe props
const { registry } = defineRegistry(catalog, {
components: {
Button: ({ props }) => (
<button className={props.variant}>{props.label}</button>
),
Card: ({ props, children }) => (
<div className="card">
<h2>{props.title}</h2>
{children}
</div>
),
Layout: ({ children, slots }) => (
<div>
<header>{slots?.header}</header>
<main>{children}</main>
<footer>{slots?.footer}</footer>
</div>
),
},
});
Spec Structure (Element Tree)
The React schema uses an element tree format:
{
"root": {
"type": "Card",
"props": { "title": "Hello" },
"children": [{ "type": "Button", "props": { "label": "Click me" } }]
}
}
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 299 lines · 41 tokens per session scan A 15c1ccc5f776
react is a skill published in the GitHub repository vercel-labs/json-render (16,056 stars, last pushed 4d ago), licensed Apache-2.0. It adds 41 tokens to every session and 2,667 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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