[BUG] Cannot bind MCP tools to ChatXAI models

[Ries0703]

Bug Description

When using tools loaded via loadMcpTools() with createReactAgent from @langchain/langgraph using ChatXAI or ChatDeepSeek, the system throws a TypeError: parameters.describe is not a function.

Reproduction Steps

Steps to reproduce the behavior:

1. Create a client using new Client() from @modelcontextprotocol/sdk/client.
2. Connect to a tool server via StdioClientTransport, e.g., tavily-mcp.
3. Load tools using loadMcpTools('tavily-mcp', client).
4. Pass these tools directly to createReactAgent() as-is, choose ChatDeepSeek or ChatXAI as the LLM.
5. Invoke the compiled agent workflow and observe the crash.

Expected Behavior

The tools should be accepted by createReactAgent() without requiring manual conversion of the parameters field to Zod schema.

Actual Behavior

Runtime error is thrown:

[Nest] 19888  - 29/04/2025, 6:06:13 pm   ERROR TypeError: Cannot read properties of undefined (reading 'typeName')
    at parseDef (C:\Users\Admin\Documents\red\p1\demo\node_modules\openai\src\_vendor\zod-to-json-schema\parseDef.ts:102:53)
    at zodToJsonSchema (C:\Users\Admin\Documents\red\p1\demo\node_modules\openai\src\_vendor\zod-to-json-schema\zodToJsonSchema.ts:26:13)
    at zodToJsonSchema (C:\Users\Admin\Documents\red\p1\demo\node_modules\openai\src\helpers\zod.ts:16:26)
    at zodFunction (C:\Users\Admin\Documents\red\p1\demo\node_modules\openai\src\helpers\zod.ts:119:21)
    at _convertToOpenAITool (C:\Users\Admin\Documents\red\p1\demo\node_modules\@langchain\xai\node_modules\@langchain\openai\dist\utils\tools.cjs:22:50)
    at _convertChatOpenAIToolTypeToOpenAITool (C:\Users\Admin\Documents\red\p1\demo\node_modules\@langchain\xai\node_modules\@langchain\openai\dist\chat_models.cjs:461:48)
    at C:\Users\Admin\Documents\red\p1\demo\node_modules\@langchain\xai\node_modules\@langchain\openai\dist\chat_models.cjs:1330:19
    at Array.map (<anonymous>)
    at ChatXAI.bindTools (C:\Users\Admin\Documents\red\p1\demo\node_modules\@langchain\xai\node_modules\@langchain\openai\dist\chat_models.cjs:1328:26)
    at createReactAgent (C:\Users\Admin\Documents\red\p1\demo\node_modules\@langchain\langgraph\src\prebuilt\react_agent_executor.ts:469:3)

Stack trace points to internal LangGraph validation when handling tools.

Environment

• OS: Windows 11
• Node.js version: 22.14.0
• Package version:
  • @langchain/langgraph: 0.2.65
  • @langchain/mcp-adapters: 0.4.2
• MCP Tool: tavily-mcp (https://docs.tavily.com/documentation/mcp#cursor)
• Transport type: stdio
• MCP Server:

Additional Context

None

Possible Solution

none

[benjamincburns]

This is actually a bug in langchain - we need to implement JSONSchema support on the XAI provider. Created langchain-ai/langchainjs#8166 to track this

[benjamincburns]

@Ries0703 Thanks for flagging this. Let's track this on the new ticket (see link in previous comment).