MCP Tool Error - "Invalid tool call structure: No preceding AIMessage with tool_call_ids"

[ldavis9000aws]

Issue Description

When using MCP tools in LibreChat, I'm occasionally encountering an error that prevents the conversation from continuing and blocks export functionality.

Error Message

{"level":"error","message":"[api/server/controllers/agents/client.js #sendCompletion] Operation aborted Invalid tool call structure: No preceding AIMessage with tool_call_ids","stack":"Error: Invalid tool call structure: No preceding AIMessage with tool_call_ids\n    at formatAssistantMessage (C:\\LibreChat\\api\\node_modules\\@librechat\\agents\\dist\\cjs\\messages\\format.cjs:161:27)\n    at formatAgentMessages (C:\\LibreChat\\api\\node_modules\\@librechat\\agents\\dist\\cjs\\messages\\format.cjs:321:35)\n    at AgentClient.chatCompletion (C:\\LibreChat\\api\\server\\controllers\\agents\\client.js:653:63)\n    at AgentClient.sendCompletion (C:\\LibreChat\\api\\server\\controllers\\agents\\client.js:406:16)\n    at AgentClient.sendMessage (C:\\LibreChat\\api\\app\\clients\\BaseClient.js:657:35)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async AgentController (C:\\LibreChat\\api\\server\\controllers\\agents\\request.js:90:20)\n    at async C:\\LibreChat\\api\\server\\routes\\agents\\chat.js:37:5"}

Impact

• Once the error occurs, I can't restart the conversation
• I'm unable to export conversations as .txt or .md files
• The error seems to happen randomly during conversations with MCP servers enabled

Environment

• LibreChat with MCP tools enabled
• Error logs can be found at "C:\LibreChat\api\logs"

Technical Analysis

Based on the error stack trace, the issue occurs in the message formatting process:

1. The error originates in formatAssistantMessage function at line 161 of messages/format.cjs
2. It seems to be related to the handling of tool calls, specifically when trying to process a tool call without a preceding AIMessage containing tool_call_ids
3. The error propagates through the AgentClient's chatCompletion and sendCompletion methods

This appears to be a race condition or state management issue in how tool calls are being tracked and associated with AI messages.

Reproduction

This error occurs randomly during conversations with MCP tools enabled, making it difficult to provide exact reproduction steps. However, it seems to happen more frequently during longer conversations with multiple tool calls.

Additional Context

Additional logs might be available in "C:\LibreChat\api\logs" which could provide more context about the specific conditions leading to this error.

[ldavis9000aws]

Claude Sonnet 3.7 can be way too proactive when creating Github issues, lol...let me know what additional info you need. It's been happening a lot with the Bedrock model lately, but I also recently upgraded from v0.7.6 to 0.7.7. Prior to that, I'd never ran into this particular issue before.

[danny-avila]

To be sure, the conversation export would be really helpful here. This is an error I throw intentionally as this exact message structure would not be accepted by Anthropic.

You mentioned you're not able to export, but we can still get an "export" of the conversation if you can still view the conversation., without using the db directly:

Steps

1. Open network tab in browser dev tools (ctrl+shift+i in chrome)
2. Then, navigate to the conversation in question.
3. Next, paste the conversation ID (from the URL) into the filter:
   
4. You should see a few requests, if you don't refresh. Preview each one till you find /api/messages:

5. Copy the response and we can start troubleshooting the exact messages you have. You can send this over discord DM or redact any sensitive parts as you deem necessary, but the exact structure of each message content field is important.

[danny-avila]

Also worth mentioning to be sure you're on dev-latest:

Updating Instructions (docker):

# Linux command to Remove all existing images
docker images -a | grep "librechat" | awk '{print $3}' | xargs docker rmi

# Windows Powershell
docker images -a | findstr "librechat" | ForEach-Object { docker rmi $_.Split()[2] }

Then follow the directions here: https://www.librechat.ai/docs/local/docker#update-librechat

[danny-avila]

also what the current agent looks like would be helpful, doing similar steps with the network tab would be good (except using agent ID, found under name in the builder form), if not an outright screenshot of the agent form.

[ldavis9000aws]

Sent the info over a DM in Discord. It will show up as a friend request with a link to a Google Doc with the info. Let me know if that's what you were looking for.

[ldavis9000aws]

I was able to export a .json file of one of the conversations.
AIMessage_tool_call_ids_issue.json

[danny-avila]

Thanks! I'm able to reproduce the issue with your payload, and I should have a fix for this soon.

[danny-avila]

resolving: #6553