{"record":{"id":"fde3150e1ca7aea1","repo":"n8n-io/n8n","slug":"tool-tool-name-returned-an-error","errorCode":null,"errorMessage":"Tool \"${tool.name}\" returned an error","messagePattern":"Tool \"(.+?)\" returned an error","errorType":"exception","errorClass":"NodeOperationError","httpStatus":null,"severity":"error","filePath":"packages/@n8n/nodes-langchain/nodes/mcp/shared/runtime.ts","lineNumber":255,"sourceCode":"\t\tconst schema: JSONSchema7 = tool.inputSchema;\n\t\tconst sanitizedToolArguments: IDataObject =\n\t\t\tschema.additionalProperties !== true\n\t\t\t\t? pick(toolArguments, Object.keys(schema.properties ?? {}))\n\t\t\t\t: toolArguments;\n\n\t\tconst result = await client.callTool(\n\t\t\t{ name: tool.name, arguments: sanitizedToolArguments },\n\t\t\tCallToolResultSchema,\n\t\t\t{\n\t\t\t\ttimeout,\n\t\t\t\tsignal: ctx.getExecutionCancelSignal(),\n\t\t\t},\n\t\t);\n\n\t\tif (node.typeVersion >= 1.3 && result.isError) {\n\t\t\tconst errorMessage =\n\t\t\t\tgetErrorDescriptionFromToolCall(result) ?? `Tool \"${tool.name}\" returned an error`;\n\t\t\tthrow new NodeOperationError(node, errorMessage, { itemIndex });\n\t\t}\n\n\t\treturnData.push({\n\t\t\tjson: {\n\t\t\t\tresponse: result.content as IDataObject,\n\t\t\t\t...(isStructuredContent(result.structuredContent) && {\n\t\t\t\t\tstructuredContent: result.structuredContent,\n\t\t\t\t}),\n\t\t\t},\n\t\t\tpairedItem: { item: itemIndex },\n\t\t});\n\t}\n}\n\n/**\n * Execute a single MCP tool call from an agent toolkit invocation.\n *\n * The agent passes `item.json.tool` (the prefixed tool name) and the tool arguments","sourceCodeStart":237,"sourceCodeEnd":273,"githubUrl":"https://github.com/n8n-io/n8n/blob/5ac6606e81f67bb9534255570cd4e86fd8101eee/packages/@n8n/nodes-langchain/nodes/mcp/shared/runtime.ts#L237-L273","documentation":"Error \"Tool \"${tool.name}\" returned an error\" thrown in n8n-io/n8n.","triggerScenarios":"Thrown at packages/@n8n/nodes-langchain/nodes/mcp/shared/runtime.ts:255 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"5ac6606e81f67bb9534255570cd4e86fd8101eee","analyzedAt":"2026-08-12T05:26:35.080Z","schemaVersion":2},"datasetVersion":"2026-08-12T13:17:24.610Z"}