### Check for existing issues

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

### What happened?

### Description:

When LiteLLM connects to an upstream Model Context Protocol (MCP) server that exposes more than 100 tools, the /mcp-rest/tools/list endpoint fails to handle pagination properly.The upstream MCP server responds with the first page of 100 tools and provides a nextCursor value for the remaining items. However, LiteLLM does not follow this cursor, nor does it expose it to the client. It returns only the first 100 tools and completely drops the pagination data. The top-level keys returned in the client response are strictly limited to ['tools', 'error', 'message'].

### Impact:

Any client application or AI agent utilizing this proxy endpoint is permanently blind to any tool that sorts past position 100 in the upstream server's list. Testing with a query parameter like limit shows that it is ignored by LiteLLM.Furthermore, attempting to bypass this via LiteLLM's native /mcp JSON-RPC endpoint as an alternative path fails with an HTTP 500 error: {"error":"MCP request failed","details":""}.

### Steps to Reproduce

1. Connect LiteLLM …