/**
* MCP Tool Error Formatter
*
* Transforms ValidationResult into MCP tool-specific error responses.
* Provides structured field-level error details for MCP tool calls.
*
* Requirements: 4.2, 4.4, 4.5
*/
import type { FieldError, ValidationResult } from "../types.js";
import type { ErrorFormatter, MCPValidationErrorResponse } from "./types.js";
/**
* MCPFormatter transforms ValidationResult to MCPValidationErrorResponse
*
* Features:
* - Formats errors for MCP tool response format
* - Includes fieldErrors array with path, message, code, expected, suggestion
* - Provides actionable suggestions for fixing errors
*
* Requirements: 4.2, 4.4, 4.5
*/
export class MCPFormatter implements ErrorFormatter<MCPValidationErrorResponse> {
/**
* Format a ValidationResult for MCP tool response
*
* @param result - The validation result to format
* @returns MCP tool-specific validation error response
*
* Requirements: 4.2, 4.4, 4.5
*/
format(result: ValidationResult): MCPValidationErrorResponse {
const fieldErrors = this.buildFieldErrors(result.errors);
const suggestion = this.buildSuggestion(result.errors);
return {
success: false,
error: "Invalid request parameters",
code: "VALIDATION_ERROR",
suggestion,
fieldErrors,
};
}
/**
* Build the fieldErrors array from field errors
*
* @param errors - Array of field errors
* @returns Array of MCP field error objects
*
* Requirements: 4.2, 4.4, 4.5
*/
private buildFieldErrors(errors: FieldError[]): MCPValidationErrorResponse["fieldErrors"] {
return errors.map((error) => ({
path: error.path,
message: error.message,
code: error.code,
expected: error.expected,
suggestion: error.suggestion,
}));
}
/**
* Build a summary suggestion from field errors
*
* @param errors - Array of field errors
* @returns Summary suggestion string
*
* Requirements: 4.2
*/
private buildSuggestion(errors: FieldError[]): string {
if (errors.length === 0) {
return "Check that all required fields are provided with valid values";
}
if (errors.length === 1) {
return errors[0].suggestion;
}
// For multiple errors, provide a summary
const fieldNames = errors.map((e) => e.path).join(", ");
return `Fix validation errors in the following fields: ${fieldNames}`;
}
}
/**
* Factory function to create an MCPFormatter instance
*
* @returns New MCPFormatter instance
*/
export function createMCPFormatter(): MCPFormatter {
return new MCPFormatter();
}
