Agent request with key error when MCP is selected for some endpoints (LiteLLM)

[psychomelet]

What happened?

All LiteLLM endpoints should function consistently regardless of MCP status.

Version Information

ghcr.io/danny-avila/librechat-dev latest 69836bf6d276 14 hours ago 1.15 GB

LibreChat latest version, using MCPs, models served by LiteLLM Proxy.

Steps to Reproduce

When MCP is enabled, certain LiteLLM endpoints (e.g., grok3, gemini pro 2.5, gemini flash 2.5) fail with key errors or unexpected behavior. These endpoints work correctly when MCP is unchecked in ui.

DeepSeek / OpenAI endpoints works in all cases.

Keys all generated by LiteLLM, but given that the error gone if keep MCP unchecked from UI, the key shall be correct.

What browsers are you seeing the problem on?

No response

Relevant log output

For example with grok3, errored about incorrect API key (even though the key is correct because without MCP it works).

May 30 03:09:24 librechat librechat[34931]: 2025-05-30 08:09:24 error: [api/server/controllers/agents/client.js #sendCompletion] Operation aborted 400 "Incorrect API key provided: sk***Hg. You can obtain an API key from https://console.x.ai."
May 30 03:09:24 librechat librechat[34931]: 2025-05-30 08:09:24 error: [api/server/controllers/agents/client.js #sendCompletion] Unhandled error type 400 "Incorrect API key provided: sk***Hg. You can obtain an API key from https://console.x.ai."
May 30 03:09:24 librechat librechat[34931]: 2025-05-30 08:09:24 error: [api/server/controllers/agents/client.js #titleConvo] Error 400 "Incorrect API key provided: sk***Hg. You can obtain an API key from https://console.x.ai."

Also with gemini pro 2.5 and gemini flash 2.5, errored about no_user_key and Google censor/filter (but again, without MCP it works).

May 30 03:15:18 librechat librechat[34931]: 2025-05-30 08:15:18 error: [handleAbortError] AI response error; aborting request: {"type":"no_user_key"}
May 30 03:15:18 librechat librechat[34931]: 2025-05-30 08:15:18 warn: AI Response error for conversation 2e25f77f-6582-4cfc-849a-36d5e039f6d2 likely caused by Google censor/filter

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