devtools

devtools is a skill for Claude Code, Codex from vercel-labs/json-render. It costs 108 tokens per session (2,161 once invoked), scanned A, original, Apache-2.0.

An inspector panel for applications that render user interfaces from JSON descriptions. It lets developers view the interface structure and observe or change its runtime state.

In plain words
What is it for?
Use it to inspect component specifications, edit state, follow live updates, review actions, browse a component catalogue, or identify the JSON key behind a page element.
Why use it?
It makes otherwise hidden generated-interface behaviour easier to inspect and debug while the app is running.

Skill for Claude CodeCodex ✓ vendor

Written for no agent in particular: nothing here depends on one.

Good fit Use it to inspect component specifications, edit state, follow live updates, review actions, browse a component catalogue, or identify the JSON key behind a page element.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vercel-labs/json-render/devtools
About the project

json-render is a framework where AI produces user interfaces as structured JSON constrained by a developer-defined component catalogue. It is for building dynamic interfaces from natural-language prompts across web and mobile frameworks.

vercel-labs/json-render · 18,711 stars · on GitHub · json-render.dev

Install

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.

Any agent
npx skills add vercel-labs/json-render --skill devtools
Clone the repo
git clone --depth 1 https://github.com/vercel-labs/json-render

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for devtools

README.md
[![agentmods](https://agentmods.dev/badge/skills/vercel-labs/json-render/devtools/github.svg)](https://agentmods.dev/skills/vercel-labs/json-render/devtools)
Your own site
<a href="https://agentmods.dev/skills/vercel-labs/json-render/devtools"><img src="https://agentmods.dev/badge/skills/vercel-labs/json-render/devtools/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for devtools

Your own site · 80×15
<a href="https://agentmods.dev/skills/vercel-labs/json-render/devtools"><img src="https://agentmods.dev/badge/skills/vercel-labs/json-render/devtools.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 108 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,161 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 14 Sept 2026
  • Snyk pass 14 Sept 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00108 $0.02161
Opus 5.5 $0.00043 $0.00864
Sonnet 5.5 $0.00022 $0.00432
Haiku 4.5 $0.00011 $0.00216

Measured 1mo ago against content hash 3dacf170385b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

devtools 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 1mo 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.

skills/devtools/SKILL.md · 186 lines

How it starts

The opening of the file, as written. The whole thing — 186 lines — stays where its author put it; the contents beside it link to each section on GitHub.

@json-render/devtools

A floating inspector panel for json-render apps. Framework-agnostic core + per-framework adapters (React, Vue, Svelte, Solid).

Production-safe: the component renders null when NODE_ENV === "production".

Install

Install the core package plus the adapter that matches the host app's renderer.

# React
npm install @json-render/devtools @json-render/devtools-react

# Vue
npm install @json-render/devtools @json-render/devtools-vue

# Svelte
npm install @json-render/devtools @json-render/devtools-svelte

# Solid
npm install @json-render/devtools @json-render/devtools-solid

Drop-in usage

Place <JsonRenderDevtools /> anywhere inside the existing <JSONUIProvider> (or framework equivalent). No other wiring required.

React

import { JsonRenderDevtools } from "@json-render/devtools-react";

<JSONUIProvider registry={registry} handlers={handlers}>
  <Renderer spec={spec} registry={registry} />
  <JsonRenderDevtools spec={spec} catalog={catalog} messages={messages} />
</JSONUIProvider>;

Vue

<script setup>
import { JsonRenderDevtools } from "@json-render/devtools-vue";
</script>

<template>
  <JSONUIProvider :registry="registry">
    <Renderer :spec="spec" :registry="registry" />
    <JsonRenderDevtools :spec="spec" :catalog="catalog" :messages="messages" />
  </JSONUIProvider>
</template>

Svelte

<script>
  import { JsonRenderDevtools } from "@json-render/devtools-svelte";
</script>

<JSONUIProvider {registry}>
  <Renderer {spec} {registry} />
  <JsonRenderDevtools {spec} {catalog} {messages} />
</JSONUIProvider>

Solid

import { JsonRenderDevtools } from "@json-render/devtools-solid";

<JSONUIProvider registry={registry}>
  <Renderer spec={spec()} registry={registry} />
  <JsonRenderDevtools
    spec={spec()}
    catalog={catalog}
    messages={messages()}
  />
</JSONUIProvider>;

Controls

  • Floating toggle appears bottom-right.
  • Hotkey: Ctrl/Cmd + Shift + J (configurable via hotkey prop).
  • Drawer is resizable; height persists to localStorage.

Read the full file on GitHub · 186 lines

Changes

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.

  1. 1mo ago First seen · 186 lines · 108 tokens per session scan A 3dacf170385b

Subscribe to this mod's changes

devtools is a skill published in the GitHub repository vercel-labs/json-render (18,711 stars, last pushed 4d ago), licensed Apache-2.0. It adds 108 tokens to every session and 2,161 once invoked, about $0.0004 per session on Opus 5.5. 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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