mcp-metro: Skill for Claude Code

.claude/skills/mcp-app-add-to-server/SKILL.md

mcp-app-add-to-server is a skill for Claude Code from OlliMakarova/mcp-metro. It costs 97 tokens per session (4,303 once invoked), scanned A, a copy of mcp-app-add-to-server, MIT.

A skill for adding interactive HTML views to existing MCP tools. MCP is a standard way for an AI coding assistant to connect to tools, while an MCP app adds a user interface that can appear in the conversation.

In plain words
What is it for?
It is for pairing MCP tools with sandboxed HTML widgets, linking them to UI resources, and configuring how those widgets are rendered.
Why use it?
It lets an MCP tool show interactive information instead of returning text alone, while keeping the tool usable by clients that do not support the interface.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is OlliMakarova/mcp-metro's own configuration. It tells Claude Code how to work on mcp-metro 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 mcp-metro configures →

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is node scripts/clone-mcp-ext-apps.js --tag latest.

Reuse

Borrowing it

Nothing to install: this file belongs to OlliMakarova/mcp-metro. 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/OlliMakarova/mcp-metro/master/.claude/skills/mcp-app-add-to-server/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/OlliMakarova/mcp-metro

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 mcp-app-add-to-server

README.md
[![agentmods](https://agentmods.dev/badge/skills/ollimakarova/mcp-metro/mcp-app-add-to-server/github.svg)](https://agentmods.dev/skills/ollimakarova/mcp-metro/mcp-app-add-to-server)
Your own site
<a href="https://agentmods.dev/skills/ollimakarova/mcp-metro/mcp-app-add-to-server"><img src="https://agentmods.dev/badge/skills/ollimakarova/mcp-metro/mcp-app-add-to-server/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 mcp-app-add-to-server

Your own site · 80×15
<a href="https://agentmods.dev/skills/ollimakarova/mcp-metro/mcp-app-add-to-server"><img src="https://agentmods.dev/badge/skills/ollimakarova/mcp-metro/mcp-app-add-to-server.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 97 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,303 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 $0.00097 $0.04303
Opus 5 $0.00048 $0.02152
Sonnet 5 $0.00019 $0.00861
Haiku 4.5 $0.00010 $0.00430

Measured 11d ago against content hash ce332e723966, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

mcp-app-add-to-server 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 11d 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 mcp-app-add-to-server — 12 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/mcp-app-add-to-server/SKILL.md · 444 lines

How it starts

The opening of the file, as written. The whole thing — 444 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Add UI to MCP Server

Enrich an existing MCP server's tools with interactive UIs using the MCP Apps SDK (@modelcontextprotocol/ext-apps).

How It Works

Existing tools get paired with HTML resources that render inline in the host's conversation. The tool continues to work for text-only clients — UI is an enhancement, not a replacement. Each tool that benefits from UI gets linked to a resource via _meta.ui.resourceUri, and the host renders that resource in a sandboxed iframe when the tool is called.

Preferred pattern: reference the widget via _meta.ui.resourceUri. Linking a tool to a separately registered ui:// resource (the tool declares _meta.ui.resourceUri; the host fetches the HTML with resources/read) is the recommended way to add UI, and the one this skill uses throughout. Prefer it over embedding the ui:// resource inline in the tool result's content[]. The referenced form lets the host fetch and cache the static shell once, review its _meta.ui (CSP, permissions, domain) before rendering, and know the widget exists before the call — which is what enables app-only tools (visibility: ["app"]) and the "UI" badge / "Launch widget" button in the Agent Tester Inspector. Reserve the embedded form for quick, one-off, fully data-dependent widgets.

Getting Reference Code

Clone or update the MCP Apps SDK repository (@modelcontextprotocol/ext-apps) using the bundled helper. The folder ./mcp-ext-apps/ is already in .gitignore and is intentionally persistent — it serves as the long-lived reference checkout that this skill (and the mcp-app-create skill) read from. Do not delete it after use.

node scripts/clone-mcp-ext-apps.js --tag latest

The script clones into ./mcp-ext-apps/ on first run, pulls the default branch on subsequent runs, and (with --tag latest) checks out the latest released npm tag so the cloned tree matches the published @modelcontextprotocol/ext-apps version. Add --json to capture machine- readable metadata (path, ref, commit) for downstream automation.

Read the full file on GitHub · 444 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. 11d ago First seen · 444 lines · 97 tokens per session scan A ce332e723966

Subscribe to this mod's changes

mcp-app-add-to-server is a skill published in the GitHub repository OlliMakarova/mcp-metro (0 stars, last pushed 1mo ago), licensed MIT. It adds 97 tokens to every session and 4,303 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to mcp-app-add-to-server, differing in 12 lines, and is treated as a copy.

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