/**
* Custom error classes for MCP tool execution errors
*/
import { McpError } from "@modelcontextprotocol/sdk/types.js";
/**
* Error thrown when an MCP protocol-level error occurs during tool execution
* (e.g., connection failures, transport errors, server crashes)
*
* Extends McpError to preserve MCP error structure (code, message, data)
* and adds stderr output from the MCP server process
*/
export class ToolCallMcpError extends McpError {
/**
* Array of stderr lines captured from the MCP server process
* This is particularly useful for stdio-based MCP servers that write
* detailed error information to stderr
*/
public readonly stderr: string[];
constructor(
mcpError: McpError,
stderr: string[]
) {
// Preserve original MCP error properties
super(mcpError.code, mcpError.message, mcpError.data);
this.name = 'ToolCallMcpError';
this.stderr = stderr;
}
}
/**
* Error thrown when an MCP tool call completes successfully at the protocol level,
* but the tool itself returns an error response (result.isError = true)
*
* This represents a logical failure in the tool execution, not a protocol failure.
* The full result object is preserved for inspection.
*/
export class ToolCallError extends Error {
/**
* The complete result object from the MCP tool call
* This includes the error response, content, and any other result properties
*/
public readonly result: {
isError?: boolean;
content: unknown[];
error?: unknown;
[key: string]: unknown;
};
constructor(result: {
isError?: boolean;
content: unknown[];
error?: unknown;
[key: string]: unknown;
}) {
// Extract error message from result content
const content = result.content as Array<{ text?: string }> | undefined;
let errorMessage = "Tool call failed";
if (content && content.length > 0) {
const firstContent = content[0];
if (firstContent && typeof firstContent === 'object' && 'text' in firstContent) {
errorMessage = firstContent.text || errorMessage;
} else if (typeof firstContent === 'string') {
errorMessage = firstContent;
}
}
// Include result in message for logging/debugging
const resultStr = JSON.stringify(result, null, 2);
super(`${errorMessage}\n\nTool call result:\n${resultStr}`);
this.name = 'ToolCallError';
this.result = result;
}
}
