Submitting an SSE MCP request from Librechat to LiteLLM broken in 0.7.8

[schwifty-brows]

What happened?

when running in 0.7.7 agent with mcp attachements were working without issue. In 0.7.8 they appear to be broken as litellm complains with

"Invalid Message bedrock requires at least one non-system message"

when further inspecting what librechat sent, this is what i see

{
  "user": "67fea0aebd23d47e2c24f16d",
  "model": "Claude 3.7 - Sonnet",
  "tools": [
    {
      "type": "function",
      "function": {
        "name": "search_confluence_mcp_comp-confluence",
        "parameters": {
          "type": "object",
          "$schema": "http://json-schema.org/draft-07/schema#",
          "required": [
            "query"
          ],
          "properties": {
            "query": {
              "type": "string",
              "description": "Search query string"
            },
            "space": {
              "anyOf": [
                {
                  "anyOf": [
                    {
                      "not": {}
                    },
                    {
                      "type": "string",
                      "description": "Optional space key"
                    }
                  ],
                  "description": "Optional space key"
                },
                {
                  "type": "null"
                }
              ],
              "description": "Optional space key"
            }
          },
          "additionalProperties": false
        },
        "description": "Search Confluence documents and pages"
      }
    }
  ],
  "stream": true,
  "messages": []
}

notice how messages is empty

this is also an issue when not using an agent

Version Information

0.7.8 latest main

Steps to Reproduce

1. load latest librechat (main)

2. make a request to latest litellm

3. see the error specified above

4. load 0.7.7 librechat

5. make a request to latest litellm

6. no error

What browsers are you seeing the problem on?

No response

Relevant log output

"Invalid Message bedrock requires at least one non-system message"

Screenshots

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[schwifty-brows]

further details

[danny-avila]

I made a simple mock MCP server of the Atlassian Confluence Search without issues (without LiteLLM):

https://github.com/danny-avila/mock_confluence_mcp

[danny-avila]

Last outlier could be the size of the tool output. It could be that the tool output is far exceeding the LLM context window, which could lead to all messages being pruned, thus the messages payload would be empty. Double-check your debug logs to determine what context window your request is using, and troubleshoot the exact length of the tool output, or better yet, token size: https://tiktokenizer.vercel.app/

[schwifty-brows]

if i dump the text return into the link above, it gives 6k and some change tokens

[danny-avila]

Try the simple mock MCP server of the Atlassian Confluence Search, see if it gives you the same issue.

https://github.com/danny-avila/mock_confluence_mcp

[schwifty-brows]

also, if i restrict the tool return to 10K or less characters, it seems to work (it executes way to many calls after to get more information)