error_handler.py•3.7 kB
"""
Decorator-based error handling for MCP entry points.
This module provides consistent error handling across all MCP tools, resources, and prompts.
"""
import functools
import json
from typing import Any, Callable, Dict, Union
def handle_mcp_errors(return_type: str = 'str') -> Callable:
"""
Decorator to handle exceptions in MCP entry points consistently.
This decorator catches all exceptions and formats them according to the expected
return type, providing consistent error responses across all MCP entry points.
Args:
return_type: The expected return type format
- 'str': Returns error as string format "Error: {message}"
- 'dict': Returns error as dict format {"error": "Operation failed: {message}"}
- 'json': Returns error as JSON string with dict format
Returns:
Decorator function that wraps MCP entry points with error handling
Example:
@mcp.tool()
@handle_mcp_errors(return_type='str')
def set_project_path(path: str, ctx: Context) -> str:
from ..services.project_management_service import ProjectManagementService
return ProjectManagementService(ctx).initialize_project(path)
@mcp.tool()
@handle_mcp_errors(return_type='dict')
def search_code_advanced(pattern: str, ctx: Context, **kwargs) -> Dict[str, Any]:
return SearchService(ctx).search_code(pattern, **kwargs)
"""
def decorator(func: Callable) -> Callable:
@functools.wraps(func)
def wrapper(*args, **kwargs) -> Union[str, Dict[str, Any]]:
try:
return func(*args, **kwargs)
except Exception as e:
error_message = str(e)
if return_type == 'dict':
return {"error": f"Operation failed: {error_message}"}
elif return_type == 'json':
return json.dumps({"error": f"Operation failed: {error_message}"})
else: # return_type == 'str' (default)
return f"Error: {error_message}"
return wrapper
return decorator
def handle_mcp_resource_errors(func: Callable) -> Callable:
"""
Specialized error handler for MCP resources that always return strings.
This is a convenience decorator specifically for @mcp.resource decorated functions
which always return string responses.
Args:
func: The MCP resource function to wrap
Returns:
Wrapped function with error handling
Example:
@mcp.resource("config://code-indexer")
@handle_mcp_resource_errors
def get_config() -> str:
ctx = mcp.get_context()
from ..services.project_management_service import ProjectManagementService
return ProjectManagementService(ctx).get_project_config()
"""
return handle_mcp_errors(return_type='str')(func)
def handle_mcp_tool_errors(return_type: str = 'str') -> Callable:
"""
Specialized error handler for MCP tools with flexible return types.
This is a convenience decorator specifically for @mcp.tool decorated functions
which may return either strings or dictionaries.
Args:
return_type: The expected return type ('str' or 'dict')
Returns:
Decorator function for MCP tools
Example:
@mcp.tool()
@handle_mcp_tool_errors(return_type='dict')
def find_files(pattern: str, ctx: Context) -> Dict[str, Any]:
from ..services.file_discovery_service import FileDiscoveryService
return FileDiscoveryService(ctx).find_files(pattern)
"""
return handle_mcp_errors(return_type=return_type)