Tool & Prompt Errors

Errors thrown during tool and prompt lookup and execution.

Overview

Tool and prompt errors are thrown when a tool or prompt cannot be found or when execution fails. Not-found errors are public and safe to expose to clients, while execution errors are internal and hide implementation details.

Error Reference

ToolNotFoundError

Thrown when a requested tool is not registered in the server.

Property	Type	Value
code	string	TOOL_NOT_FOUND
statusCode	number	404
isPublic	boolean	true

new ToolNotFoundError(toolName: string)

Example:

import { ToolNotFoundError } from '@frontmcp/sdk';

const tool = registry.get(name);
if (!tool) {
  throw new ToolNotFoundError(name);
}

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ToolExecutionError

Thrown when a tool’s execute() method throws an unexpected error. This is an internal error — the original error details are hidden from clients.

Property	Type	Value
code	string	TOOL_EXECUTION_ERROR
statusCode	number	500
isPublic	boolean	false
originalError	Error | undefined	The underlying cause

new ToolExecutionError(toolName: string, originalError?: Error)

Example:

import { ToolExecutionError } from '@frontmcp/sdk';

try {
  await tool.execute(input);
} catch (error) {
  throw new ToolExecutionError('my_tool', error);
}

ToolExecutionError extends InternalMcpError. Clients receive a generic message with an errorId for support correlation, not the original stack trace.

---

PromptNotFoundError

Thrown when a requested prompt is not registered in the server.

Property	Type	Value
code	string	PROMPT_NOT_FOUND
statusCode	number	404
isPublic	boolean	true

new PromptNotFoundError(promptName: string)

Example:

import { PromptNotFoundError } from '@frontmcp/sdk';

throw new PromptNotFoundError('summarize');
// "Prompt not found: summarize"

---

PromptExecutionError

Thrown when a prompt’s execute() method throws an unexpected error. This is an internal error.

Property	Type	Value
code	string	PROMPT_EXECUTION_FAILED
statusCode	number	500
isPublic	boolean	false
promptName	string	The prompt that failed
originalError	Error | undefined	The underlying cause

new PromptExecutionError(promptName: string, cause?: Error)

Example:

import { PromptExecutionError } from '@frontmcp/sdk';

try {
  await prompt.execute(args);
} catch (error) {
  throw new PromptExecutionError('summarize', error);
}