mcp-builder

Q: How do I install mcp-builder?

Run npx skills add https://github.com/composio-community/awesome-claude-plugins --skill mcp-builder in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/mcp-builder/ (personal) or .claude/skills/mcp-builder/ (project).

by composio-communityAI & Agents

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).

Installs: 1.6K
Last 24h: +47
Trending rank: #3519
Security: Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/composio-community/awesome-claude-plugins --skill mcp-builder

01
Install
Run the command in your project. The CLI asks which agents to install for.
02
Describe the task
Ask your agent for something this skill covers. It loads mcp-builder automatically when relevant.
03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

MCP Server Development Guide

Overview

To create high-quality MCP (Model Context Protocol) servers that enable LLMs to effectively interact with external services, use this skill. An MCP server provides tools that allow LLMs to access external services and APIs.

High-Level Workflow

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

Phase 1: Deep Research and Planning

Agent-Centric Design Principles

Build for Workflows, Not Just API Endpoints:

Don't simply wrap existing API endpoints - build thoughtful, high-impact workflow tools
Consolidate related operations (e.g., schedule_event that both checks availability and creates event)
Focus on tools that enable complete tasks, not just individual API calls

Optimize for Limited Context:

Agents have constrained context windows - make every token count
Return high-signal information, not exhaustive data dumps
Provide "concise" vs "detailed" response format options
Default to human-readable identifiers over technical codes

Design Actionable Error Messages:

Error messages should guide agents toward correct usage patterns
Suggest specific next steps: "Try using filter='active_only' to reduce results"
Make errors educational, not just diagnostic

Study MCP Protocol Documentation

Fetch the latest MCP protocol documentation: Use WebFetch to load: https://modelcontextprotocol.io/llms-full.txt

For Python implementations:

Python SDK: https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md

For Node/TypeScript implementations:

TypeScript SDK: https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/main/README.md

Phase 2: Implementation

Set Up Project Structure

For Python:

Create a single .py file or organize into modules if complex
Use the MCP Python SDK for tool registration
Define Pydantic models for input validation

For Node/TypeScript:

Create proper project structure
Set up package.json and tsconfig.json
Use MCP TypeScript SDK
Define Zod schemas for input validation

Implement Core Infrastructure First

Create shared utilities before implementing tools:

API request helper functions
Error handling utilities
Response formatting functions (JSON and Markdown)
Pagination helpers
Authentication/token management

Implement Tools Systematically

For each tool:

Define Input Schema:

Use Pydantic (Python) or Zod (TypeScript) for validation
Include proper constraints (min/max length, regex patterns)
Provide clear, descriptive field descriptions

Write Comprehensive Docstrings:

One-line summary of what the tool does
Detailed explanation of purpose and functionality
Explicit parameter types with examples
Complete return type schema
Usage examples

Add Tool Annotations:

readOnlyHint: true (for read-only operations)
destructiveHint: false (for non-destructive operations)
idempotentHint: true (if repeated calls have same effect)
openWorldHint: true (if interacting with external systems)

Phase 3: Review and Refine

Code Quality Review

Review the code for:

DRY Principle: No duplicated code between tools
Composability: Shared logic extracted into functions
Consistency: Similar operations return similar formats
Error Handling: All external calls have error handling
Type Safety: Full type coverage
Documentation: Every tool has comprehensive docstrings

Phase 4: Create Evaluations

Create comprehensive evaluations to test MCP server effectiveness.

Each evaluation question must be:

Independent: Not dependent on other questions
Read-only: Only non-destructive operations required
Complex: Requiring multiple tool calls and deep exploration
Realistic: Based on real use cases
Verifiable: Single, clear answer that can be verified

Best Practices Summary

Build for workflows, not just API endpoints
Optimize for limited context windows
Design actionable error messages
Follow natural task subdivisions
Use evaluation-driven development
Study framework documentation thoroughly
Implement core infrastructure first
Add proper tool annotations
Test with realistic scenarios

FAQ

What does the mcp-builder skill do?

How do I install mcp-builder?

Run npx skills add https://github.com/composio-community/awesome-claude-plugins --skill mcp-builder in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/mcp-builder/ (personal) or .claude/skills/mcp-builder/ (project).

Which AI agents can use mcp-builder?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is mcp-builder safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains mcp-builder?

It is published by composio-community in composio-community/awesome-claude-plugins. It has 1,624 recorded installs.