MCP Developer

What it does

When your agent uses it

• Building an MCP server that exposes internal tools to an AI client
• Adding resource providers with URI templates to an existing server
• Choosing and configuring stdio, SSE or HTTP transport
• Debugging a tool call that returns a malformed response
• Validating tool inputs with Zod or Pydantic schemas

Example prompts

• “Scaffold a TypeScript MCP server with one tool that looks up order status and validates input with Zod.”
• “Our Python MCP server returns malformed JSON-RPC errors, so run the inspector and find the cause.”
• “Expose the docs folder as MCP resources with URI templates.”
• “Switch this server from stdio to HTTP transport and add authentication.”

Requirements

• Node.js for the TypeScript SDK or Python for the Python SDK

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

1. 1Analyze requirements — Identify data sources, tools needed, and client apps
2. 2Initialize project — npx @modelcontextprotocol/create-server my-server (TypeScript) or pip install mcp + scaffold (Python)
3. 3Design protocol — Define resource URIs, tool schemas (Zod/Pydantic), and prompt templates
4. 4Implement — Register tools and resource handlers; configure transport (stdio/SSE/HTTP)
5. 5Test — Run npx @modelcontextprotocol/inspector to verify protocol compliance interactively; confirm tools appear, schemas accept valid…
6. 6Deploy — Package, add auth/rate-limiting, configure env vars, monitor

What it can do on your machine

Read from SKILL.md and the folder at commit 1be15d8. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • npx
  • pip

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • github.com
  • synergetic.solutions
  • jeffallan.github.io

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

MCP Developer loads about 1.5k tokens when it runs, and up to ~13k if it reads all its reference files. Until then it costs about 100 tokens; SKILL.md has 316 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~100

When it runs · the whole SKILL.md, loaded when a task matches

~1.5k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~13k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Jeffallan/claude-skills at commit 1be15d8, republished under its MIT licence (© Jeffallan). 316 words, ~1,467 tokens.

name

mcp-developer

description

Use when building, debugging, or extending MCP servers or clients that connect AI systems with external tools and data sources. Invoke to implement tool handlers, configure resource providers, set up stdio/HTTP/SSE transport layers, validate schemas with Zod or Pydantic, debug protocol compliance issues, or scaffold complete MCP server/client projects using TypeScript or Python SDKs.

license

MIT

metadata.author

https://github.com/Jeffallan

metadata.company

https://synergetic.solutions

metadata.version

1.1.0

metadata.domain

api-architecture

metadata.triggers

MCP, Model Context Protocol, MCP server, MCP client, Claude integration, AI tools, context protocol, JSON-RPC

metadata.role

specialist

metadata.scope

implementation

metadata.output-format

code

metadata.related-skills

fastapi-expert, typescript-pro, security-reviewer, devops-engineer

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";

const server = new McpServer({ name: "my-server", version: "1.1.0" });

// Register a tool with validated input schema
server.tool(
  "get_weather",
  "Fetch current weather for a location",
  {
    location: z.string().min(1).describe("City name or coordinates"),
    units: z.enum(["celsius", "fahrenheit"]).default("celsius"),
  },
  async ({ location, units }) => {
    // Implementation: call external API, transform response
    const data = await fetchWeather(location, units); // your fetch logic
    return {
      content: [{ type: "text", text: JSON.stringify(data) }],
    };
  }
);

// Register a resource provider
server.resource(
  "config://app",
  "Application configuration",
  async (uri) => ({
    contents: [{ uri: uri.href, text: JSON.stringify(getConfig()), mimeType: "application/json" }],
  })
);

const transport = new StdioServerTransport();
await server.connect(transport);

from mcp.server.fastmcp import FastMCP
from pydantic import BaseModel, Field

mcp = FastMCP("my-server")

class WeatherInput(BaseModel):
    location: str = Field(..., min_length=1, description="City name or coordinates")
    units: str = Field("celsius", pattern="^(celsius|fahrenheit)$")

@mcp.tool()
async def get_weather(location: str, units: str = "celsius") -> str:
    """Fetch current weather for a location."""
    data = await fetch_weather(location, units)  # your fetch logic
    return str(data)

@mcp.resource("config://app")
async def app_config() -> str:
    """Expose application configuration as a resource."""
    return json.dumps(get_config())

if __name__ == "__main__":
    mcp.run()  # defaults to stdio transport

Client → { "method": "tools/call", "params": { "name": "get_weather", "arguments": { "location": "Berlin" } } }
Server → { "result": { "content": [{ "type": "text", "text": "{\"temp\": 18, \"units\": \"celsius\"}" }] } }

© Jeffallan, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 5 other files (references) in skills/mcp-developer of Jeffallan/claude-skills.

• SKILL.md
• references/protocol.md
• references/python-sdk.md
• references/resources.md
• references/tools.md
• references/typescript-sdk.md

Open the folder on GitHubat commit 1be15d8