echo-mcp: Skill for Claude Code

.agents/skills/mcp-apps-builder/SKILL.md

mcp-apps-builder is a skill for Claude Code, Codex from ZenlixAI/echo-mcp. It costs 139 tokens per session (3,484 once invoked), scanned A, a copy of mcp-apps-builder, MIT.

A guide for building and changing MCP servers with the mcp-use framework. MCP servers provide tools, data, or other capabilities that an AI agent can use.

In plain words
What is it for?
Creating, modifying, debugging, or reviewing MCP server tools, resources, prompts, and widgets.
Why use it?
It directs developers to the relevant implementation patterns and checks whether an existing MCP project should be extended or a new one created.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is ZenlixAI/echo-mcp's own configuration. It tells Claude Code and Codex how to work on echo-mcp 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 echo-mcp configures →

Reuse

Borrowing it

Nothing to install: this file belongs to ZenlixAI/echo-mcp. 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/ZenlixAI/echo-mcp/main/.agents/skills/mcp-apps-builder/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/ZenlixAI/echo-mcp

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 mcp-apps-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/zenlixai/echo-mcp/mcp-apps-builder.svg)](https://agentmods.dev/skills/zenlixai/echo-mcp/mcp-apps-builder)
Your own site
<a href="https://agentmods.dev/skills/zenlixai/echo-mcp/mcp-apps-builder"><img src="https://agentmods.dev/badge/skills/zenlixai/echo-mcp/mcp-apps-builder.svg" alt="Measured on agentmods" height="20"></a>
Per session 139 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,484 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 88% 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 $0.00139 $0.03484
Opus 5 $0.00069 $0.01742
Sonnet 5 $0.00028 $0.00697
Haiku 4.5 $0.00014 $0.00348

Measured 8d ago against content hash 9c847ecd6cef, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

mcp-apps-builder 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 8d 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

88% identical to mcp-apps-builder — 86 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.

.agents/skills/mcp-apps-builder/SKILL.md · 374 lines

How it starts

The opening of the file, as written. The whole thing — 374 lines — stays where its author put it; the contents beside it link to each section on GitHub.

IMPORTANT: How to Use This Skill

This file provides a NAVIGATION GUIDE ONLY. Before implementing any MCP server features, you MUST:

  1. Read this overview to understand which reference files are relevant
  2. ALWAYS read the specific reference file(s) for the features you're implementing
  3. Apply the detailed patterns from those files to your implementation

Do NOT rely solely on the quick reference examples in this file - they are minimal examples only. The reference files contain critical best practices, security considerations, and advanced patterns.


MCP Server Best Practices

Comprehensive guide for building production-ready MCP servers with tools, resources, prompts, and widgets using mcp-use.

⚠️ FIRST: New Project or Existing Project?

Before doing anything else, determine whether you are inside an existing mcp-use project.

Detection: Check the workspace for a package.json that lists "mcp-use" as a dependency, OR any .ts file that imports from "mcp-use/server".

├─ mcp-use project FOUND → Do NOT scaffold. You are already in a project.
│  └─ Skip to "Quick Navigation" below to add features.
│
├─ NO mcp-use project (empty dir, unrelated project, or greenfield)
│  └─ Scaffold first with npx create-mcp-use-app, then add features.
│     See "Scaffolding a New Project" below.
│
└─ Inside an UNRELATED project (e.g. Next.js app) and user wants an MCP server
   └─ Ask the user where to create it, then scaffold in that directory.
      Do NOT scaffold inside an existing unrelated project root.

NEVER manually create MCPServer boilerplate, package.json, or project structure by hand. The CLI sets up TypeScript config, dev scripts, inspector integration, hot reload, and widget compilation that are difficult to replicate manually.


Scaffolding a New Project

npx create-mcp-use-app my-server
cd my-server
npm run dev

For full scaffolding details and CLI flags, see quickstart.md.

Read the full file on GitHub · 374 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. 8d ago First seen · 374 lines · 139 tokens per session scan A 9c847ecd6cef

Subscribe to this mod's changes

mcp-apps-builder is a skill published in the GitHub repository ZenlixAI/echo-mcp (8 stars, last pushed 5mo ago), licensed MIT. It adds 139 tokens to every session and 3,484 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to mcp-apps-builder, differing in 86 lines, and is treated as a copy.

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