MCP Builder

MCP Builder

Build a working MCP server from a description of the tools you need. Produces a deployable Python server using FastMCP.

Workflow

Step 1: Define What to Expose

Ask what the server needs to provide:

• Tools -- Functions Claude can call (API wrappers, calculations, file operations)
• Resources -- Data Claude can read (database records, config, documents)
• Prompts -- Reusable prompt templates with parameters

A brief like "MCP server for querying our customer database" is enough.

Step 2: Scaffold the Server

pip install fastmcp

Create the server file. The server instance MUST be at module level:

from fastmcp import FastMCP

# MUST be at module level for FastMCP Cloud
mcp = FastMCP("My Server")

@mcp.tool()
async def search_customers(query: str) -> str:
    """Search customers by name or email."""
    # Implementation here
    return f"Found customers matching: {query}"

@mcp.resource("customers://{customer_id}")
async def get_customer(customer_id: str) -> str:
    """Get customer details by ID."""
    return f"Customer {customer_id} details"