mcpapp-colorpicker: Skill for Claude Code

.claude/skills/create-mcp-app/SKILL.md

Create MCP App is a skill for Claude Code from elbruno/mcpapp-colorpicker. It costs 76 tokens per session (2,862 once invoked), scanned A, a copy of create-mcp-app, MIT.

A development guide for building MCP Apps: interactive web interfaces that run inside hosts such as Claude Desktop and connect to an MCP tool. It explains how the tool, its data, and the HTML interface fit together.

In plain words
What is it for?
Use it to scaffold an MCP App, add a UI to an existing MCP server, register the interface, or choose an approach for React or plain JavaScript.
Why use it?
It removes the guesswork around linking an MCP tool to a user interface and making that interface work inside an MCP-enabled host.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is elbruno/mcpapp-colorpicker's own configuration. It tells Claude Code how to work on mcpapp-colorpicker itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mcpapp-colorpicker configures →

Reuse

Borrowing it

Nothing to install: this file belongs to elbruno/mcpapp-colorpicker. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/elbruno/mcpapp-colorpicker/master/.claude/skills/create-mcp-app/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/elbruno/mcpapp-colorpicker

Made for: Claude Code.

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 Create MCP App

README.md
[![agentmods](https://agentmods.dev/badge/skills/elbruno/mcpapp-colorpicker/create-mcp-app/github.svg)](https://agentmods.dev/skills/elbruno/mcpapp-colorpicker/create-mcp-app)
Your own site
<a href="https://agentmods.dev/skills/elbruno/mcpapp-colorpicker/create-mcp-app"><img src="https://agentmods.dev/badge/skills/elbruno/mcpapp-colorpicker/create-mcp-app/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 Create MCP App

Your own site · 80×15
<a href="https://agentmods.dev/skills/elbruno/mcpapp-colorpicker/create-mcp-app"><img src="https://agentmods.dev/badge/skills/elbruno/mcpapp-colorpicker/create-mcp-app.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 76 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,862 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.
Origin 92% copy Near-identical to another mod 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 $0.00076 $0.02862
Opus 5 $0.00038 $0.01431
Sonnet 5 $0.00015 $0.00572
Haiku 4.5 $0.00008 $0.00286

Measured 10d ago against content hash 61eb20c068ce, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

Create MCP App 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 10d 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.

Origin

This is a copy

92% identical to create-mcp-app — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/create-mcp-app/SKILL.md · 343 lines

How it starts

The opening of the file, as written. The whole thing — 343 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Create MCP App

Build interactive UIs that run inside MCP-enabled hosts like Claude Desktop. An MCP App combines an MCP tool with an HTML resource to display rich, interactive content.

Core Concept: Tool + Resource

Every MCP App requires two parts linked together:

  1. Tool - Called by the LLM/host, returns data
  2. Resource - Serves the bundled HTML UI that displays the data
  3. Link - The tool's _meta.ui.resourceUri references the resource
Host calls tool → Server returns result → Host renders resource UI → UI receives result

Quick Start Decision Tree

Framework Selection

Framework SDK Support Best For
React useApp hook provided Teams familiar with React
Vanilla JS Manual lifecycle Simple apps, no build complexity
Vue/Svelte/Preact/Solid Manual lifecycle Framework preference

Project Context

Adding to existing MCP server:

  • Import registerAppTool, registerAppResource from SDK
  • Add tool registration with _meta.ui.resourceUri
  • Add resource registration serving bundled HTML

Creating new MCP server:

  • Set up server with transport (stdio or HTTP)
  • Register tools and resources
  • Configure build system with vite-plugin-singlefile

Getting Reference Code

Clone the SDK repository for working examples and API documentation:

git clone --branch "v$(npm view @modelcontextprotocol/ext-apps version)" --depth 1 https://github.com/modelcontextprotocol/ext-apps.git /tmp/mcp-ext-apps

Framework Templates

Learn and adapt from /tmp/mcp-ext-apps/examples/basic-server-{framework}/:

Template Key Files
basic-server-vanillajs/ server.ts, src/mcp-app.ts, mcp-app.html
basic-server-react/ server.ts, src/mcp-app.tsx (uses useApp hook)
basic-server-vue/ server.ts, src/App.vue
basic-server-svelte/ server.ts, src/App.svelte
basic-server-preact/ server.ts, src/mcp-app.tsx
basic-server-solid/ server.ts, src/mcp-app.tsx

Read the full file on GitHub · 343 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. 10d ago First seen · 343 lines · 76 tokens per session scan A 61eb20c068ce

Subscribe to this mod's changes

Create MCP App is a skill published in the GitHub repository elbruno/mcpapp-colorpicker (13 stars, last pushed 5mo ago), licensed MIT. It adds 76 tokens to every session and 2,862 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to create-mcp-app, differing in 6 lines, and is treated as a copy.

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