can1357/oh-my-pi · error · Error

Unknown tool: ${name}

Error message

Unknown tool: ${name}

What it means

handleToolCall() dispatches MCP tool invocations through the TOOL_HANDLERS lookup table. If the requested tool name is not a registered mnemopi_* handler, it throws this error naming the unknown tool. Only tools listed in TOOLS/getToolDefinitions() are valid.

Source

Thrown at packages/mnemopi/src/mcp-tools.ts:965

	mnemopi_validate: handleValidate,
	mnemopi_get: handleGet,
	mnemopi_triple_add: handleTripleAdd,
	mnemopi_triple_query: handleTripleQuery,
	mnemopi_scratchpad_write: handleScratchpadWrite,
	mnemopi_scratchpad_read: handleScratchpadRead,
	mnemopi_scratchpad_clear: handleScratchpadClear,
	mnemopi_export: handleExport,
	mnemopi_update: handleUpdate,
	mnemopi_forget: handleForget,
	mnemopi_import: handleImport,
	mnemopi_diagnose: handleDiagnose,
	mnemopi_graph_query: handleGraphQuery,
	mnemopi_graph_link: handleGraphLink,
};

export async function handleToolCall(name: string, args: ToolArguments = {}): Promise<ToolResult> {
	const handler = TOOL_HANDLERS[name];
	if (handler === undefined) throw new Error(`Unknown tool: ${name}`);
	return handler(args);
}
export function getToolDefinitions(): readonly ToolDefinition[] {
	return TOOLS;
}

View on GitHub (pinned to 9690622007)

Solutions

1. Call getToolDefinitions() (or tools/list over MCP) and use exactly one of the returned names.
2. Fix the tool name typo in the client/config; names are mnemopi_graph_query, mnemopi_graph_link, etc.
3. Refresh the client's cached tool list so it matches the running server version.
4. If a needed tool is genuinely missing, add a handler to TOOL_HANDLERS and a definition to TOOLS.

Example fix

// before
const result = await handleToolCall('mnemopi_graph_search', args); // wrong name
// after
const names = getToolDefinitions().map(t => t.name);
if (!names.includes('mnemopi_graph_query')) throw new Error('tool unavailable');
const result = await handleToolCall('mnemopi_graph_query', args);

import { getToolDefinitions, handleToolCall } from './mcp-tools';
const knownTools = new Set(getToolDefinitions().map(t => t.name));
async function safeToolCall(name, args) {
  if (!knownTools.has(name)) {
    throw new Error(`Tool '${name}' not available. Valid: ${[...knownTools].join(', ')}`);
  }
  return handleToolCall(name, args);
}

function isKnownTool(name) {
  return TOOL_HANDLERS[name] !== undefined;
}

try {
  const result = await handleToolCall(name, args);
} catch (err) {
  if (err instanceof Error && err.message.startsWith('Unknown tool:')) {
    const available = getToolDefinitions().map(t => t.name);
    return { error: { code: -32601, message: `${err.message} Available: ${available.join(', ')}` } };
  }
  throw err;
}

When it happens

Trigger: Calling handleToolCall('some_tool') where 'some_tool' is not a key in TOOL_HANDLERS — e.g. a typo, a tool from a different MCP server, or a client using a stale tool list.

Common situations: LLM clients hallucinating tool names, cached tool lists from an older/newer server version, tools renamed between releases, or calling tools from another MCP server through this one.

Related errors

• Received toolcall_delta for non-toolCall content
• Anthropic SDK request did not expose a stream response
• Anthropic cache refresh request did not expose a raw respons
• ENXIO
• Refusing to download onto a non-regular file: ${absolutePath

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/b72ab414995dc362. Report an issue: GitHub.