### Check for existing issues

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

### What happened?

the `add2` function can be invoked successfully via `:4000/toolset/tool001/mcp`

### Steps to Reproduce

1. An MCP Toolset (`:4000/toolset/tool001/mcp`) aggregates specific MCP functions from multiple MCP servers. 2. When I go to one of the MCP servers and—under "Select which tools users can call"—toggle the `add2` function off (and save) before toggling it back on (and saving), the `add2` function appears when I access the Toolset URL, but invoking it results in a 403 error. 3. However, the `add2` function can be invoked successfully via `:4000/mcp`.

### Relevant log output

```shell { "name": "FastMCP-add2", "metadata": { "status": "failure", "headers": { "content-type": "application/json" }, "agent_id": null, "endpoint": "/mcp/tools/call", "user_agent": "", "user_api_key": "litellm_proxy_master_key", "error_information": { "traceback": "Traceback (most recent call last):\n File \"/app/.venv/lib/python3.13/site-packages/litellm/proxy/_experimental/mcp_server/server.py\", line 2950, in call…