# Creating MCP Tools
## Overview
This guide explains how to create your own MCP tools using the FastMCP framework.
## Basic Tool Structure
Here's a simple example of creating an MCP tool:
```python
from fastmcp import FastMCP
mcp = FastMCP("YourToolName")
@mcp.tool()
def your_tool(parameter: str) -> dict:
"""Tool description here"""
# Your implementation
return {"success": True, "result": result}
if __name__ == "__main__":
mcp.run(transport="stdio")
```
## Example Tools
### Calculator Tool
**File:** `src/mcp/tools/calculator.py`
Performs mathematical calculations:
```python
from fastmcp import FastMCP
mcp = FastMCP("Calculator")
@mcp.tool()
def calculate(expression: str) -> dict:
"""Evaluate a mathematical expression"""
try:
result = eval(expression)
return {"success": True, "result": result}
except Exception as e:
return {"success": False, "error": str(e)}
if __name__ == "__main__":
mcp.run(transport="stdio")
```
### Stock Tool
**File:** `src/mcp/tools/stock.py`
Query stock prices and information:
- `query_stock(symbol)`: Query a single stock by symbol (e.g., 'AAPL', 'GOOGL')
- `query_multiple_stocks(symbols)`: Query multiple stocks at once (comma-separated)
- `list_available_stocks()`: List all available stock symbols
**Supported stock symbols:** AAPL, GOOGL, MSFT, TSLA, AMZN, META, NVDA, BABA, TSM, NFLX
### Email Tool
**File:** `src/mcp/tools/email_tool.py`
Send emails and manage recipients:
- `list_recipients()`: List all available recipients
- `get_recipient(email)`: Get recipient information by email address
- `send_email(to_email, subject, body, is_html)`: Send email to a single recipient
**Note:** Email tool SMTP configuration is in `mcp_config.yaml` under `mcp.servers.{server-name}.smtp`
## Tool Configuration
Add your tool to `mcp_config.yaml`:
```yaml
mcp:
servers:
local-stdio-your-tool:
enabled: true
type: stdio
command: python
args:
- src/mcp/tools/your_tool.py
```
## Best Practices
1. **Error Handling:** Always return structured error responses
2. **Documentation:** Provide clear tool descriptions
3. **Type Hints:** Use type hints for better IDE support
4. **Testing:** Test tools individually before adding to config
5. **Logging:** Use appropriate logging levels
## Transport Types
Tools can use different transport types:
- **stdio**: Standard input/output (for local Python scripts)
- **sse**: Server-Sent Events (for remote servers)
- **http**: HTTP requests (for REST APIs)
For stdio tools, use `mcp.run(transport="stdio")` in your script.
