### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

The issue which was reported in #23337 and suppose to be fixed in https://github.com/BerriAI/litellm/commit/212b249e38e407bf9103e6c7de6690f7dcfa1207 still occurs in v1.83.10-stable.

### Steps to Reproduce

```yaml model_list: - model_name: "gemini-2.5-pro" litellm_params: model: "vertex_ai/gemini-2.5-pro" vertex_location: "europe-west4" web_search_options: {} ```

```ssh curl -sS \ -X POST "$LITELLM_BASE_URL/v1/chat/completions" \ -H "Authorization: Bearer $LITELLM_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "model": "gemini-2.5-pro", "messages": [ { "role": "user", "content": "Who won the Hungarian election in 2026?" } ], "tools": [ { "type": "function", "function": { "name": "notion_search", "description": "Search Notion", "parameters": {"type": "object", "properties": {"query": {"type": "string"}}} } } ] }' | jq .

{ "error": { "message": "li…