mcp-builder

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).

2.55x

Quality

66%

Does it follow best practices?

Impact

97%

2.55x

Average score across 3 eval scenarios

Securityby

Advisory

Suggest reviewing before use

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Evaluation results

98%

81%

Build a Python MCP Server for the JSONPlaceholder API

Python MCP server implementation

Criteria

Without context

With context

Server naming convention

100%

Tool naming with service prefix

100%

FastMCP with @mcp.tool decorator

100%

Tool annotations in decorator

100%

Pydantic v2 model_config

100%

CHARACTER_LIMIT constant

100%

Pagination metadata returned

100%

Dual response formats

100%

Shared utility functions

60%

100%

Async/await for I/O

100%

Actionable error messages

12%

100%

Stderr for logging

50%

100%

62%

Build a TypeScript MCP Server for the DummyJSON API

TypeScript MCP server implementation

Criteria

Without context

With context

Server naming convention

100%

McpServer import path

100%

registerTool usage

100%

Project directory structure

50%

100%

Zod schemas with .strict()

100%

TypeScript strict mode

100%

No 'any' types

100%

Tool annotations set

100%

CHARACTER_LIMIT constant

100%

Pagination metadata returned

100%

Tool names include service prefix

100%

Build succeeds

100%

94%

33%

Create an Evaluation Suite for an Open Library MCP Server

MCP server evaluation file creation

Criteria

Without context

With context

Correct XML structure

25%

100%

Exactly 10 Q&A pairs

100%

Simple scalar answers

100%

Questions require multi-step reasoning

100%

Questions avoid trivial keyword search

100%

Read-only question framing

100%

Question independence

100%

Answer format specification

50%

75%

Topic diversity

100%

50%

Stable answers

66%

100%

Repository: davepoon/buildwithclaude
Commit: 7cc63f3

Evaluated: 28 days ago
Agent: Claude Code
Model: Claude Sonnet 4.6

Table of Contents

Build a Python MCP Server for the JSONPlaceholder API Build a TypeScript MCP Server for the DummyJSON API Create an Evaluation Suite for an Open Library MCP Server

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