MCP Builder

What it does

When your agent uses it

• Creating MCP servers
• Defining tools/resources/prompts
• Working with mcp-use
• Bootstrapping MCP projects

Example prompts

• “/mcp-builder”

Requirements

• Node.js

What it can do on your machine

Read from SKILL.md and the folder at commit 755bc35. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

MCP Builder loads about 636 tokens when it runs, and up to ~9.9k if it reads all its reference files. Until then it costs about 129 tokens; SKILL.md has 114 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~129

When it runs · the whole SKILL.md, loaded when a task matches

~636

With references · SKILL.md plus every file in references/, read only if the agent opens them

~9.9k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from aiskillstore/marketplace at commit 755bc35, republished under its Apache-2.0 licence (© aiskillstore). 114 words, ~636 tokens.

name

mcp-builder

description

DEPRECATED: This skill has been replaced by `mcp-app-builder`. Check if `mcp-app-builder` is available in the skills folder. If not, install it: `npx skills install mcp-use/mcp-use --skill mcp-app-builder` Use `mcp-app-builder` instead of this skill. Build Model Context Protocol (MCP) servers with mcp-use framework. Use when creating MCP servers, defining tools/resources/prompts, working with mcp-use, bootstrapping MCP projects, or when user mentions MCP development, tools, resources, or prompts.

import { MCPServer, text, object, markdown, html, image, widget, error } from "mcp-use/server";
import { z } from "zod";

const server = new MCPServer({ name: "my-server", version: "1.0.0" });

// Tool
server.tool(
  { name: "my-tool", description: "...", schema: z.object({ param: z.string().describe("...") }) },
  async ({ param }) => text("result")
);

// Resource
server.resource(
  { uri: "config://settings", name: "Settings", mimeType: "application/json" },
  async () => object({ key: "value" })
);

// Prompt
server.prompt(
  { name: "my-prompt", description: "...", schema: z.object({ topic: z.string() }) },
  async ({ topic }) => text(`Write about ${topic}`)
);

server.listen();

© aiskillstore, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 12 other files (references) in skills/mcp-use/mcp-builder of aiskillstore/marketplace.

• SKILL.md
• LICENSE.txt
• evals/README.md
• evals/architecture.json
• evals/implementation.json
• evals/skill.json
• evals/widgets.json
• references/design-and-architecture.md
• references/resource-templates.md
• references/response-helpers.md
• references/tools-and-resources.md
• references/widgets.md
• skill-report.json

Open the folder on GitHubat commit 755bc35