#!/usr/bin/env python """ 05_logging.py - MCP logging capabilities This example demonstrates the various logging levels and patterns available through the MCP protocol for debugging and monitoring. To run: python 05_logging.py To see debug logs: Set log_level="DEBUG" when creating MCPApp """ import asyncio import time import traceback from typing import Annotated, Optional from arcade_mcp_server import Context, MCPApp # Create the app with debug logging app = MCPApp(name="logging_examples", version="0.1.0", log_level="DEBUG") @app.tool async def demonstrate_log_levels( context: Context, message: Annotated[str, "Base message to log at different levels"] ) -> Annotated[dict, "Summary of logged messages"]: """Demonstrate all MCP logging levels.""" # Log at each level levels = ["debug", "info", "warning", "error"] logged = {} for level in levels: log_message = f"[{level.upper()}] {message}" await context.log(level, log_message) logged[level] = log_message return {"logged_messages": logged, "note": "Check your MCP client to see these messages"} @app.tool async def timed_operation( context: Context, operation_name: Annotated[str, "Name of the operation"], duration_seconds: Annotated[float, "How long the operation takes"] = 2.0, ) -> Annotated[dict, "Operation timing details"]: """Perform a timed operation with detailed logging.""" start_time = time.time() # Log operation start await context.log.info( f"Starting operation: {operation_name} (expected duration: {duration_seconds}s)" ) # Simulate work with progress logging steps = 5 for i in range(steps): await context.log.debug(f"Progress: step {i + 1}/{steps} ({(i + 1) / steps * 100:.0f}%)") await asyncio.sleep(duration_seconds / steps) # Calculate results end_time = time.time() actual_duration = end_time - start_time # Log completion await context.log.info(f"Completed operation: {operation_name} in {actual_duration:.2f}s") return { "operation": operation_name, "expected_duration": duration_seconds, "actual_duration": round(actual_duration, 2), "start_time": start_time, "end_time": end_time, } @app.tool async def error_handling_example( context: Context, should_fail: Annotated[bool, "Whether to simulate an error"], error_type: Annotated[str, "Type of error to simulate"] = "ValueError", ) -> Annotated[dict, "Result or error details"]: """Demonstrate error logging and handling.""" try: await context.log.debug(f"Error handling test: should_fail={should_fail}") if should_fail: if error_type == "ValueError": raise ValueError("This is a simulated value error") # noqa: TRY301 elif error_type == "KeyError": raise KeyError("missing_key") # noqa: TRY301 elif error_type == "ZeroDivisionError": result = 1 / 0 return {"result": result} else: raise Exception(f"Generic error of type: {error_type}") # noqa: TRY002, TRY301 # Success case await context.log.info("Operation completed successfully") except Exception as e: # Log the error with details await context.log.error(f"Operation failed with {type(e).__name__}: {e!s}") # Log traceback separately at debug level await context.log.debug(f"Traceback:\n{traceback.format_exc()}") return { "status": "error", "error_type": type(e).__name__, "error_message": str(e), "handled": True, } else: return {"status": "success", "message": "No errors occurred"} @app.tool async def structured_logging( context: Context, user_action: Annotated[str, "Action the user is performing"], metadata: Annotated[dict | None, "Additional metadata to log"] = None, ) -> Annotated[str, "Confirmation message"]: """Demonstrate structured logging patterns.""" # Log main action await context.log.info( f"User action: {user_action} (user_id: {context.user_id or 'anonymous'})" ) # Log additional details at debug level await context.log.debug( f"Context details: {len(context.secrets) if context.secrets else 0} secrets available" ) # Log metadata if provided if metadata: await context.log.debug(f"Custom metadata: {metadata}") return f"Logged user action: {user_action}" @app.tool async def batch_processing_logs( context: Context, items: Annotated[list[str], "Items to process"], fail_on_item: Annotated[Optional[str], "Item that should fail"] = None, ) -> Annotated[dict, "Processing results with detailed logs"]: """Process items with detailed logging for each step.""" results: dict[str, list] = {"successful": [], "failed": []} await context.log.info(f"Starting batch processing of {len(items)} items") for i, item in enumerate(items): try: # Log item start await context.log.debug(f"Processing item {i + 1}/{len(items)}: {item}") # Simulate failure if requested if item == fail_on_item: raise ValueError(f"Simulated failure for item: {item}") # noqa: TRY301 # Simulate processing await asyncio.sleep(0.1) results["successful"].append(item) except Exception as e: await context.log.warning(f"Failed to process '{item}': {e!s}") results["failed"].append({"item": item, "error": str(e)}) # Log summary await context.log.info( f"Batch processing complete: {len(results['successful'])} successful, " f"{len(results['failed'])} failed", ) return results if __name__ == "__main__": # Run the server app.run(host="127.0.0.1", port=8000)