Building Your First MCP Server with Kiro's Spec-Driven Development (Part 3: Build and Test)

Kiro: I'll create the project structure for the Developer Tools MCP server.

Creating directory structure:
- developer_tools_mcp/
- developer_tools_mcp/__init__.py

Creating pyproject.toml with project metadata...

[Files created]
✓ developer_tools_mcp/__init__.py
✓ pyproject.toml

The project structure is now set up. The pyproject.toml includes:
- Project name and version
- Python version requirement (3.10+)
- FastMCP dependency
- Project metadata

Task 1.1 is complete. Ready to move to task 1.2?

developer-tools-mcp/
├── developer_tools_mcp/
│   ├── __init__.py
│   └── server.py
├── pyproject.toml
└── README.md

@mcp.tool()
async def format_code(code: str, language: Literal["python", "javascript", "json"]) -> str:
    """Format code snippets in various programming languages."""
    # Implementation

@mcp.resource("regex://common-patterns")
async def common_regex_patterns() -> str:
    """Provide common regex patterns."""
    # Return JSON data

async def format_code(code: str, language: str) -> str:
    # Implementation

def format_code(
    code: str,
    language: Literal["python", "javascript", "json"]
) -> str:

# Valid calls
format_code("print('hello')", "python")  ✓
format_code("{}", "json")  ✓

# Invalid calls
format_code("code", "ruby")  ✗ - "ruby" not in Literal
format_code("code", 123)  ✗ - wrong type

try:
    # Main logic
    if condition:
        return result
    else:
        raise ValueError("Descriptive error message")
except SpecificException as e:
    raise ValueError(f"Context: {str(e)}")
except Exception as e:
    raise ValueError(f"Generic error: {str(e)}")

"""
Format code snippets in various programming languages.

Args:
    code: The code string to format
    language: The programming language (python, javascript, or json)

Returns:
    Formatted code string

Raises:
    ValueError: If the code cannot be formatted or language is unsupported
"""

@mcp.resource("regex://common-patterns")
async def common_regex_patterns() -> str:
    patterns = {
        "email": {
            "pattern": r"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$",
            "description": "Validates email addresses",
            "example": "user@example.com"
        }
    }
    return json.dumps(patterns, indent=2)

# Navigate to your project directory
cd developer-tools-mcp

# Run the server
python <main_server_file_name>.py

FastMCP Development Server
Server: Developer Tools
Tools: 4 registered
Resources: 2 registered

Available tools:
  - format_code: Format code snippets in various programming languages
  - generate_uuid: Generate UUIDs in different formats
  - encode_decode: Encode or decode text using various encoding schemes
  - calculate_hash: Calculate cryptographic hash of text

Available resources:
  - regex://common-patterns: Common regex patterns
  - http://status-codes: HTTP status codes reference

Server running on stdio transport...
Press Ctrl+C to stop

# Install fastmcp with inspector support
pip install "fastmcp[inspector]"

# Run the inspector
fastmcp dev <name_of_your_main_mcp_server.py>

# Check that your server file exists
ls -la <main_mcp_server_file>.py

# Run the server locally
python3 developer_tools_mcp_server.py

{
  "mcpServers": {
    "mcpdoc-fastmcp": {
          "command": "uvx",
          "args": ["--from","mcpdoc","mcpdoc", "--urls", "FastMCP:https://gofastmcp.com/llms.txt","--transport", "stdio"],
          "env": {
            "FASTMCP_LOG_LEVEL": "ERROR"
          },
          "disabled": false,
          "autoApprove": []
        },
        "mcpdoc-mcp-protocol": {
          "command": "uvx",
          "args": ["--from","mcpdoc","mcpdoc", "--urls", "MCPProtocolDocs:https://modelcontextprotocol.io/llms.txt","--transport", "stdio"],
          "env": {
            "FASTMCP_LOG_LEVEL": "ERROR"
          },
          "disabled": false,
          "autoApprove": []
        }
      },
    "developer-tools": {
      "command": "python3",
      "args": ["path/to/your/dev_tools_mcp_server.py"],
      "env": {},
      "disabled": false,
      "autoApprove": ["format_code", "generate_uuid", "encode_decode", "calculate_hash"]
    }
  }

Can you use the format_code tool to format this Python code:
def hello(name):
  print(f"Hello, {name}!")

def hello(name):
    print(f"Hello, {name}!")

I'm working on this Python function but the formatting is messy. Can you clean it up?

def calculate_total(items):
  total=0
  for item in items:
    total+=item['price']*item['quantity']
  return total