I encountered an Error: 400 status code (no body) when using the creatReactAgent method

[loverara]

library version

"langchain": "^0.3.19",
"@langchain/community": "^0.3.32",
"@langchain/core": "^0.3.40",
"@langchain/langgraph": "^0.2.49",
"@langchain/mcp-adapters": "^0.3.3",
"@langchain/openai": "^0.4.4"

The tools used are from the MCP server converted by @ langchain/mcp adapters

error messages
[NEST] 2025-03-31 16:26:46 error [AIFaucet.rootOutput] Error: 400 status code (no body) at Function.generate (/Users/loverara/Documents/code_workspace/vscode_workspace/ifuncun/agent_template/node_modules/openai/src/error.ts:72:14) at OpenAI.makeStatusError (/Users/loverara/Documents/code_workspace/vscode_workspace/ifuncun/agent_template/node_modules/openai/src/core.ts:443:21) at OpenAI.makeRequest (/Users/loverara/Documents/code_workspace/vscode_workspace/ifuncun/agent_template/node_modules/openai/src/core.ts:507:24) at process.processTicksAndRejections (node:internal/process/task_queues:95:5) at async /Users/loverara/Documents/code_workspace/vscode_workspace/ifuncun/agent_template/node_modules/@langchain/openai/dist/chat_models.cjs:1528:29

The error message I received when debugging to method completionWithRetry is
'{"object":"error","message":"\\"auto\\" tool choice requires --enable-auto-tool-choice and --tool-call-parser to be set","type":"BadRequestError","param":null,"code":400}'

[benjamincburns]

Hi @loverara - I think we're going to need more details on this. The error log and message you posted isn't familiar to me at all, and I don't think it comes this or any other langchain library, though I could be mistaken!

If you'd like help troubleshooting this could you please include a minimum reproducible example?

[phpmac]

Please provide code examples or change the model

[AyushNaptick]

Hi team,

I am getting the below error during the createReactAgent function call with gpt-4o model. Can you please check and let me know what are the possible issues

 this.model = new ChatOpenAI({
      modelName: 'gpt-4o',
      openAIApiKey: // KEY,
      temperature: 0,
    });
const transport = new StdioClientTransport({
        command: "npx",
        args: ["-y", "mongodb-lens@latest", "MY_MONGO_DB_URL"]
      });
await this.clientMongo.connect(transport);
      const tools = await loadMcpTools("MongoDBMCP", this.clientMongo, {
        // Whether to throw errors if a tool fails to load (optional, default: true)
        throwOnLoadError: true,
        // Whether to prefix tool names with the server name (optional, default: false)
        prefixToolNameWithServerName: false,
        // Optional additional prefix for tool names (optional, default: "")
        additionalToolNamePrefix: "",
      });


 const agent = createReactAgent({ llm: this.model, tools });   
      const agentResponse = await agent.invoke({               // after calling this function I am getting the below error.
        messages: [{ role: "user", content: body.content }],
      });

TypeError: Cannot read properties of undefined (reading 'typeName')
    at parseDef (/Users/LangchainNest/node_modules/openai/src/_vendor/zod-to-json-schema/parseDef.ts:102:53)
    at zodToJsonSchema (/Users/LangchainNest/node_modules/openai/src/_vendor/zod-to-json-schema/zodToJsonSchema.ts:26:13)

[benjamincburns]

Closing this as the original poster has not replied. @AyushNaptick you are experiencing a different problem to the original poster. Please do not post comments on issues unrelated to your problem. Instead, open new issues. In your case I believe your problem is very likely resolved with the latest versions of @langchain/core, @langchain/mcp-adapters, and @langchain/openai. Please make sure that you have updated to latest versions of ALL of these libraries and retest. Then if you are still having issues, please open a new issue with a complete description and minimal reproducible example.