Guide · Agent skill
How to use the MCP Server Developer agent skill
Updated · written with AI from the project's own documentation and checked against our catalogue data
The MCP Server Developer skill (mcp-developer) is an agent skill that gives your AI assistant working knowledge of the Model Context Protocol (MCP), a standard way to connect AI assistants to outside tools and data. This guide is for developers who want the agent to help build or debug an MCP server or client. After reading it, you will know what the skill does, how to install it, how to phrase requests so it activates, and what to check before you trust the result.
MCP Server DeveloperJeffallan/claude-skills · MIT Download the skill Quick start
- 1Download and unzip. Download the mcp-developer ZIP from this page and unzip it into a folder named mcp-developer.
- 2Place the skill folder. Move the folder to ~/.claude/skills/ for personal use or to .claude/skills/ in your project. Alternatively, upload the ZIP under Settings → Capabilities → Skills.
- 3Install prerequisites. Make sure Node.js with npx is available for TypeScript, or Python with pip install mcp for Python, and have Zod or Pydantic ready.
- 4Ask for what you need. Describe your MCP server goal in plain language, naming the data source and language.
- 5Run the Inspector. Start npx @modelcontextprotocol/inspector and confirm tools appear and error responses are valid JSON-RPC 2.0.
- 6Fix and re-test. If validation or responses fail, correct the schema or handler and re-run the Inspector until it passes.
What an agent skill is and what this one does
An agent skill is a folder containing a SKILL.md file and optional reference files. When installed, the agent reads the skill's instructions when a request matches the skill's description, and follows its workflow.
The mcp-developer skill covers building, debugging, and extending MCP servers or clients. According to its description, it helps implement tool handlers, configure resource providers, set up stdio, HTTP or SSE transport layers, validate schemas with Zod or Pydantic, debug protocol compliance issues, and scaffold complete MCP server or client projects using TypeScript or Python SDKs.
- Scaffolds a new MCP server or client project
- Writes tool handlers and resource providers with input validation
- Sets up stdio, HTTP or SSE transports
- Walks through protocol errors using the MCP Inspector
- Includes reference notes on the protocol, both SDKs, tools, and resources
Install the mcp-developer skill
Download the skill ZIP from this page and unzip it. Then place the resulting folder in one of these locations:
For a personal install available across projects, put it in ~/.claude/skills/. For a single project, put it in that project's .claude/skills/ folder.
You can also upload the ZIP in the Claude apps under Settings → Capabilities → Skills.
- Personal: ~/.claude/skills/
- Project only: .claude/skills/ inside your project folder
- Claude apps: Settings → Capabilities → Skills, then upload the ZIP
Prerequisites for TypeScript and Python projects
The skill's workflow relies on tools you need to have available. For TypeScript projects you need Node.js with npx, which is used to run @modelcontextprotocol/create-server and the Inspector. For Python projects you need Python with pip install mcp.
For schema validation, use Zod in TypeScript or Pydantic in Python. If your server calls third-party services, you need your own API keys or credentials.
- TypeScript: Node.js with npx
- Python: pip install mcp (the Python SDK examples also use pydantic)
- Schema validation: Zod (TypeScript) or Pydantic (Python)
- Your own API keys or credentials for any external service
npx @modelcontextprotocol/create-server my-serverTrigger the skill with natural requests
You do not need a special command. Describe the task in plain language that matches the skill's purpose. Mentioning MCP, Model Context Protocol, or MCP server helps the agent pick the right skill.
Good requests name the goal and the constraints, for example the data source and the language you want.
- "Scaffold a TypeScript MCP server that exposes our internal orders API as a tool."
- "My MCP server returns malformed JSON-RPC responses. Help me find out why."
- "Add a Zod-validated tool that looks up a customer by ID, using stdio transport."
- "Write a Python MCP server with Pydantic input validation that reads config as a resource."
Test your server with the MCP Inspector
The skill's workflow ends each build with testing. Run the Inspector to check protocol compliance interactively. Confirm that your tools appear, that schemas accept valid inputs, and that error responses are well-formed JSON-RPC 2.0.
If schema validation fails, the workflow says to read the Zod or Pydantic error output, fix the schema, and re-run the Inspector. If a tool call returns a malformed response, check transport serialisation, fix the handler, and test again.
npx @modelcontextprotocol/inspectorReview the example code before using it
The skill includes a TypeScript example that registers a tool with a Zod schema and a resource at config://app, using stdio transport. It also includes a Python example using FastMCP with a Pydantic-style model and the @mcp.tool() and @mcp.resource() decorators.
The examples use placeholder helpers such as fetchWeather and get_config that you must write yourself. The skill's example output shows a tools/call request and a result with a text content item.
- Fetch logic, configuration, and credential handling are yours to write
- Check every tool input against its schema before connecting real systems
Client → { "method": "tools/call", "params": { "name": "get_weather", "arguments": { "location": "Berlin" } } }
Server → { "result": { "content": [{ "type": "text", "text": "{\"temp\": 18, \"units\": \"celsius\"}" }] } }Safety notes: scripts and network access
This skill runs scripts and uses the network. The npx commands fetch and run packages, and the servers you build may call external APIs. Review any command before you run it and confirm which packages it pulls in.
The skill's guidance says to add authentication, authorization, and rate limiting before deployment. The skill does not enforce or verify those controls in your code, so you must check them yourself. Never hardcode credentials; use environment variables instead.
- Read commands before running them, especially npx installs
- Do not expose sensitive data in resource content
- Add auth and rate limiting yourself, then verify them
- Keep API keys out of source files
What people use it for
- Connecting an AI assistant to an internal API by writing a custom tool handler
- Exposing a database schema or config file as a resource the assistant can read
- Debugging an MCP server that fails schema validation
- Scaffolding a new TypeScript or Python MCP project with a starting structure
- Choosing between stdio, HTTP, or SSE transport for a server
Frequently asked questions
How do I install the mcp-developer skill?
Download the ZIP from this page and unzip it into ~/.claude/skills/ for personal use or into a project's .claude/skills/ folder. You can also upload the ZIP in the Claude apps under Settings → Capabilities → Skills.
What do I need before using this skill?
For TypeScript projects you need Node.js with npx. For Python projects you need Python with pip install mcp. You also need Zod or Pydantic for validation, plus your own credentials if the server calls external services.
Is the mcp-developer skill free to use?
The skill is listed under the MIT licence, as shown on this page. Check the licence file in the repository for the full terms before redistributing it.
Can I use this skill if I only want to use existing MCP servers?
Not really. The skill is for building and debugging MCP servers and clients. If you only need to connect to existing servers without writing code, this skill is not the right fit.
Why does my MCP server fail schema validation?
Read the Zod or Pydantic error output to see which field failed, fix the schema definition, and re-run the MCP Inspector with npx @modelcontextprotocol/inspector. The skill's workflow follows this loop.
Does the skill make my server secure for production?
No. The skill recommends adding authentication, authorization, and rate limiting, but it does not enforce or verify those controls in your code. You need to review and test them yourself before deploying.
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Our verdict
This skill suits developers and teams in TypeScript or Python who are building a custom MCP server for an internal API or database, or who need help debugging schema and JSON-RPC errors. If you only want to use existing MCP servers without writing code, or you need a production-ready deployment with security enforced for you, pick a different resource or review the security work yourself.
Download the skill