mcp-builder

mcp-builder is an open-source frontend skill for Claude Code and compatible agents, published by anthropics. Its author describes it as: “Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or service…”. The project has 170k stars on GitHub and ships custom license terms, so review them before reuse. Add it to your setup with `/plugin marketplace add anthropics/skills`.

What mcp-builder does

Create MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. The quality of an MCP server is measured by how well it enables LLMs to accomplish real-world tasks.

Installation

Add mcp-builder to your agent with:

/plugin marketplace add anthropics/skills

Always review a skill's source before installing it. This command comes from the skill's public repository; the linked repo is the source of truth for exact setup steps.

What's inside

The SKILL.md for mcp-builder is organised into these sections:

• Overview
• 🚀 High-Level Workflow
• Phase 1: Deep Research and Planning
• Phase 2: Implementation
• Phase 3: Review and Test
• Phase 4: Create Evaluations
• 📚 Documentation Library
• Core MCP Documentation (Load First)
• SDK Documentation (Load During Phase 1/2)
• Language-Specific Implementation Guides (Load During Phase 2)
• Evaluation Guide (Load During Phase 4)

When to use it

Reach for mcp-builder when you want frontend help from your agent without writing the same instructions every session. Load the skill and the agent picks it up automatically for relevant tasks.

Strengths

• Ships in anthropics/skills, an established project with 170,235 GitHub stars
• Actively maintained (recent commits)

Things to check

• No license declared — confirm terms with the author before reuse

Topics

Frequently asked questions

What does mcp-builder do?

Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).

How do I install mcp-builder?

Run /plugin marketplace add anthropics/skills in your agent, then reload your skills. Review the source at https://github.com/anthropics/skills before installing.

Is mcp-builder free to use?

mcp-builder is publicly available on GitHub, but anthropics has not declared a standard open-source license (Complete terms in LICENSE.txt). Confirm the terms with the author before reusing it.

Where does mcp-builder come from?

mcp-builder ships inside anthropics/skills, a repository that contains 21 catalogued skills in total. The repository's 170,235 GitHub stars apply to that whole collection, not to this skill on its own.