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 skills add sammcj/agentic-coding --skill create-mcp-appgit clone --depth 1 https://github.com/sammcj/agentic-codingWrote 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.
[](https://agentmods.dev/skills/sammcj/agentic-coding/create-mcp-app)<a href="https://agentmods.dev/skills/sammcj/agentic-coding/create-mcp-app"><img src="https://agentmods.dev/badge/skills/sammcj/agentic-coding/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.
<a href="https://agentmods.dev/skills/sammcj/agentic-coding/create-mcp-app"><img src="https://agentmods.dev/badge/skills/sammcj/agentic-coding/create-mcp-app.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00069 | $0.02903 |
| Opus 5.5 | $0.00028 | $0.01161 |
| Sonnet 5.5 | $0.00014 | $0.00581 |
| Haiku 4.5 | $0.00007 | $0.00290 |
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 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.
Copies of this mod
3 near-identical copies found in the catalogue:
- Create MCP App — 92% identical, 6 lines differ
- Create-MCP-App — 92% identical, 7 lines differ
- Create MCP App — 92% identical, 6 lines differ
How it starts
The opening of the file, as written. The whole thing — 345 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:
- Tool - Called by the LLM/host, returns data
- Resource - Serves the bundled HTML UI that displays the data
- Link - The tool's
_meta.ui.resourceUrireferences 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 |
Note that if the user prefers to write MCP Servers in Golang or Rust you should ask the user if they have a specific framework in mind for that language and if not help them search for a suitable framework / library that supports MCP Apps.
Project Context
Adding to existing MCP server:
- Import
registerAppTool,registerAppResourcefrom 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 |
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.
- 1mo ago First seen · 345 lines · 69 tokens per session scan A 1b3acd45a208
create-mcp-app is a skill published in the GitHub repository sammcj/agentic-coding (164 stars, last pushed 5d ago), licensed Apache-2.0. It adds 69 tokens to every session and 2,903 once invoked, about $0.0003 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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