This file is byte-identical to the first copy the registry indexed, one of 6 indexed copies. Same content hash, so the same checks give both the same grade.
mcp-builder from letta-ai/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
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).
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# 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. The quality of an MCP server is measured by how well it enables LLMs to accomplish real-world tasks using the tools provided.
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# Process
## 🚀 High-Level Workflow
Creating a high-quality MCP server involves four main phases:
### Phase 1: Deep Research and Planning
#### 1.1 Understand Agent-Centric Design Principles
Before diving into implementation, understand how to design tools for AI agents by reviewing these 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
- Consider what workflows agents actually need to accomplish
**Optimize for Limited Context:**
- Agents have constrained context windows - make every token count
…
The line at the top of this page pins the label git:20251219.b3de744, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.
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pass: Size between 200 bytes and 200 KB (13552 bytes)
pass: No zero-width or bidi control characters
pass: No instruction hidden inside an HTML comment
pass: No link to an exfiltration or paste host
pass: No credential-shaped string
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Source
GitHub
letta-ai/skills · 156 stars · license a license file GitHub does not identify · pushed 2026-10-01 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_rm4rl4tvvayp7ro3
GET https://markdownregistry.com/api/v1/resolve?ref=letta-ai/skills/mcp-builder
GET https://markdownregistry.com/api/v1/blob/b1010e90adcb8fd6bf57640df34ab6454fbf7e4216e150a4620f7caccadc4e63
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
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enuno/unifi-mcp-server · .agents/skills/mcp-builder/SKILL.md · Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external…
