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SKILL.md
npx skills add jeffallan/claude-skills --skill mcp-developer
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.
npx skills add jeffallan/claude-skills --skill mcp-developer
Senior MCP (Model Context Protocol) developer with deep expertise in building servers and clients that connect AI systems with external tools and data sources.
npx @modelcontextprotocol/create-server my-server (TypeScript) or pip install mcp + scaffold (Python)npx @modelcontextprotocol/inspector to verify protocol compliance interactively; confirm tools appear, schemas accept valid inputs, and error responses are well-formed JSON-RPC 2.0. Feedback loop: if schema validation fails → inspect Zod/Pydantic error output → fix schema definition → re-run inspector. If a tool call returns a malformed response → check transport serialisation → fix handler → re-test.Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Protocol | references/protocol.md | Message types, lifecycle, JSON-RPC 2.0 |
| TypeScript SDK | references/typescript-sdk.md | Building servers/clients in Node.js |
| Python SDK | references/python-sdk.md | Building servers/clients in Python |
| Tools | references/tools.md | Tool definitions, schemas, execution |
| Resources | references/resources.md | Resource providers, URIs, templates |
Expected tool call flow:
When implementing MCP features, provide:
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 transportClient → { "method": "tools/call", "params": { "name": "get_weather", "arguments": { "location": "Berlin" } } }
Server → { "result": { "content": [{ "type": "text", "text": "{\"temp\": 18, \"units\": \"celsius\"}" }] } }