### Check for existing issues

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

### What happened?

I added LiteLLM as an MCP via the OpenAPI spec. I'm trying to invoke the toolcall API (`/mcp-rest/tools/call`), but it keeps erroring out with HTTP 500. The problem seems to be that the OpenAPI specs are missing all the parameter documentation.

Looking at https://docs.litellm.ai/docs/mcp_rest_api, I see that I have required body parameters `server_id`, `name`, and `arguments`.

``` curl -s -X POST http://localhost:4000/mcp-rest/tools/call \ -H "Authorization: Bearer sk-1234" \ -H "Content-Type: application/json" \ -d '{ "server_id": "17a4490465f74d3696caf12b30220166", "name": "places_api-getPlaces", "arguments": {} }' | jq . ```

But the API docs don't list any of these requirements, and that confuses the LLM when I generate an MCP from the OpenAPI specs, not allowing it to call this tool at all.

<img width="1449" height="625" alt="Image" src="https://github.com/user-attachments/assets/67828763-b2c0-497a-824a-aaa10efd82ed" />

### Steps to Reproduce

1. Visit the internal API docs https://www.litellm.org/#/mcp/call_tool_…