---
name: "anthropics/skills mcp-builder — four-phase MCP server skill"
description: "Use when building a high-quality MCP server skill (Python FastMCP or Node MCP SDK)."
---

# anthropics/skills mcp-builder — four-phase MCP server skill

## When
Use when an LLM must call an external API through well-named tools, not a one-off script.

## Stop
Never ship tools without actionable errors. Never put secrets in the skill body.

## Steps
1. List tools
2. Explore with read-only operations
3. Write 10 complex, realistic questions
4. Solve each yourself to verify the answer

## Load
mcp-builder SKILL.md + reference/. SDK docs. No production deploy.