[Bug Fix] Validate the MCP server name after splitting MCP {serverName}-{toolName}

[aaron-chen-aips]

Title

Validate the MCP server name after splitting MCP {serverName}-{toolName}, as some MCP tool has hyphen (default separator) in the toolName and Litellm proxy will take the first part as the server name

Relevant issues

Fixes #16908

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Type

🐛 Bug Fix

Changes

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[krrishdholakia]

@aaron-chen-aips this feels a bit clunky and error prone, can we try another separator? e.g. / ? cc: @uc4w6c for feedback

[aaron-chen-aips]

@aaron-chen-aips this feels a bit clunky and error prone, can we try another separator? e.g. / ? cc: @uc4w6c for feedback

Hey thanks @krrishdholakia - of course, just not sure if it's used in the URL somewhere as / may break the routing
Also Claude code uses similar formatting like {serverName}__{toolName} so it won't conflict with single hyphen

[uc4w6c]

@aaron-chen-aips
Thank you for your work.
Looking at the implementation here:
https://github.com/BerriAI/litellm/blob/main/litellm/proxy/_experimental/mcp_server/server.py#L1324

I was thinking that we could apply a similar approach when calling tools — i.e., if there is only one allowed_mcp_server, we can omit the prefix, and if there are multiple, we can extract the server name from the prefix.
That way, the current delimiter format could still work without changing it.

[aaron-chen-aips]

@aaron-chen-aips Thank you for your work. Looking at the implementation here: https://github.com/BerriAI/litellm/blob/main/litellm/proxy/_experimental/mcp_server/server.py#L1324

I was thinking that we could apply a similar approach when calling tools — i.e., if there is only one allowed_mcp_server, we can omit the prefix, and if there are multiple, we can extract the server name from the prefix. That way, the current delimiter format could still work without changing it.

Hey thanks @uc4w6c - I am not sure this would solve the issue. My current situation is I have multiple MCP servers in the config and one of them having - in the tool name.
When the MCP client passing in only the tool name, even with your suggested fix, litellm will treat the first par as server name and throwing errors

[krrishdholakia]

can we just check if the split string actually exists as a valid server name?

[aaron-chen-aips]

Thanks - updated the PR to check if split serverName exists @krrishdholakia @uc4w6c

[aaron-chen-aips]

can we just check if the split string actually exists as a valid server name?

Actually just re-think on this, this is still not ideal, as from the screenshot, backstage has a tool named backstage-search

So it will pass the check, because backstage is also the server name, it will still treat backstage as server name and search name. So ideally still have a uncommon separator so it won't exist in the tool name