MCP Builder

This guide helps developers build MCP servers for integrating external APIs and services. The quality of an MCP server is measured by how well it enables LLMs to accomplish real-world tasks.

AI, LLMs & AgentsOfficial Plugin marketplace

Install

Claude Code plugin
/plugin marketplace add anthropics/skills

Then run /plugin to install the skill set that includes it. In Claude.ai and the Claude app, Anthropic skills are built in: turn them on in Settings → Capabilities.

skills CLI (Claude Code, Cursor, Codex and more)
npx skills add anthropics/skills --skill mcp-builder
Manual install
git clone --depth 1 https://github.com/anthropics/skills.git /tmp/skills
mkdir -p ~/.claude/skills
cp -r /tmp/skills/skills/mcp-builder ~/.claude/skills/mcp-builder

Personal skills live in ~/.claude/skills. Use .claude/skills in a project folder to share a skill with your team.

What this skill does

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).

Trigger phrases

Claude loads this skill automatically when you say things like:

“MCP server”“Model Context Protocol”“build MCP”“API integration”“MCP tools”“external service integration”

How it works

  1. Deep Research and Planning: Study MCP protocol documentation and modern design patterns
  2. Implementation: Set up project structure, create core infrastructure (API client, error handling)
  3. Review and Test: Evaluate code quality, ensure type coverage, test using MCP Inspector
  4. Create Evaluations: Develop comprehensive tests with realistic questions

When to use it

  • When building MCP servers for API integration
  • When creating tools for LLM-external service interaction
  • When integrating Claude with external services

Best practices

  • Use TypeScript as the preferred language
  • Create comprehensive evaluations with 10+ complex questions
  • Eliminate duplication and ensure proper error handling

From the SKILL.md

# MCP Server Development Guide

## Overview

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.

---

# Process

## 🚀 High-Level Workflow

Creating a high-quality MCP server involves four main phases:

### Phase 1: Deep Research and Planning

#### 1.1 Understand Modern MCP Design

**API Coverage vs. Workflow Tools:**
Balance comprehensive API endpoint coverage with specialized workflow tools. Workflow tools can be more convenient for specific tasks, while comprehensive coverage gives agents flexibility to compose operations. Performance varies by client—some clients benefit from code execution that combines basic tools, while others work better with higher-level workflows. When uncertain, prioritize comprehensive API coverage.

**Tool Naming and Discoverability:**
Clear, descriptive tool names help agents find the right tools quickly. Use consistent prefixes (e.g., `github_create_issue`, `github_list_repos`) and action-oriented naming.

**Context Management:**
Agents benefit from concise tool descriptions and the ability to filter/paginate results. Design tools that return focused, relevant data. Some clients support code execution which can help agents filter and process data efficiently.

**Actionable Error Messages:**
Read the full skill on GitHub

Details

Skill name
mcp-builder
Path
skills/mcp-builder/SKILL.md

FAQ

What does the MCP Builder skill 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 the MCP Builder skill?

Claude Code plugin: /plugin marketplace add anthropics/skills. Skills go in ~/.claude/skills (personal) or .claude/skills (project), and Claude loads them automatically when a task matches the description.

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