Build production-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use this skill when the user wants to create, scaffold, or implement an MCP server for any API or service, in any language. Triggers include requests to "build an MCP server", "create MCP tools", "implement MCP", "add tools for [service]", "connect [service] via MCP", or any task involving MCP server development, tool design, or MCP architecture decisions.
View on GitHubmcp-builder/skills/mcp-builder/SKILL.md
February 4, 2026
Select agents to install to:
npx add-skill https://github.com/runlayer/plugins/blob/main/mcp-builder/skills/mcp-builder/SKILL.md -a claude-code --skill mcp-builderInstallation paths:
.claude/skills/mcp-builder/# MCP Server Builder Build MCP servers that enable LLMs to accomplish real-world tasks through well-designed tools. Server quality is measured by how effectively agents can use the tools, not by API coverage alone. ## Before You Start **Ask the user which programming language they want to use before doing anything else.** Use AskUserQuestion to prompt for their preferred language. Do not proceed until they answer. Then load the corresponding language-specific reference from `references/`: - **TypeScript** → read `references/typescript.md` - **Python** → read `references/python.md` - **Other** → use the language-agnostic patterns in `references/guidelines.md` and adapt to the chosen language Apply the language-specific conventions (naming, SDK, validation library, project structure, idioms) from the loaded reference throughout the entire build. ## Development Process Follow four phases in order: 1. **Research & Plan** — Study the target API (endpoints, auth, data models, rate limits, pagination). Plan tool coverage. Prioritize comprehensive API coverage over workflow shortcuts when uncertain. 2. **Implement** — Build infrastructure first (API client, auth, errors, formatters), then tools incrementally. 3. **Review & Test** — Build, lint, test with MCP Inspector. Review for duplication, consistent errors, type coverage. 4. **Evaluate** — Create 10 complex realistic questions requiring multiple tool calls with stable verifiable answers. ## Architecture Decisions Determine these upfront: **Transport:** - `stdio` — local/CLI tools, single user, simple setup - `Streamable HTTP` — remote/cloud, multi-client, serverless. Avoid SSE (deprecated). **State:** - Stateless (recommended for remote) — fresh server per request, horizontal scaling, no session leaks - Stateful — when session continuity is required **Auth:** - OAuth 2.1 — remote servers with user identity - API key via env vars — simpler integrations - None — local-only tools **Language conventions (appli