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Serious question, as I’m starting to go through this process myself - Is it possible for the customer to provide their own bearer tokens (generated however) th

Serious question, as I’m starting to go through this process myself - Is it possible for the customer to provide their own bearer tokens (generated however) that the LLM can pass along to the MCP server? This was the closest to a workable security I’ve looked at. I don’t know if that is all that well supported by Chat GUI/web clients (user supplied tokens), but should be possible when calling an LLM through an API style call, right (if you add additional pass thru headers)?

eric-burel 1y ago
The LLM doesn't intervene much actually, it just tells what tool to call. It's your MCP implementation that does the heavy lifting. So yeah you can always shove a key somewhere in your app context and pass it to the tool call. But I think the point of other comments is that the MCP protocol is kinda clueless about how to standardize that within the protocol itself.
- arscan 1y ago
  I think an important thing to note is the MCP client is a distinct thing from the ‘LLM’ architecturally, though many LLM providers also have MCP client implementations (via their chat ui or desktop / cli implementations). In general, I’d say it’s not a good idea to pass bearer tokens to the LLM provider and keep that to the MCP client. But your client has to be interoperable with the MCP server at the auth level, which is flakey at the moment across the ecosystem of generic MCP clients and servers as noted.
cyberax 1y ago
> but should be possible when calling an LLM through an API style call, right (if you add additional pass thru headers Nope. I assumed as much and even implemented the bearer token authentication in the MCP server that I wanted to expose. Then I tried to connect it to ChatGPT, and it turns out to NOT be supported at all. Your options are either no authentication whatsoever or OAuth with dynamic client registration. Claude at least allows the static OAuth registration (you supply client_id and client_secret).

eric-burel 1y ago

The LLM doesn't intervene much actually, it just tells what tool to call. It's your MCP implementation that does the heavy lifting. So yeah you can always shove a key somewhere in your app context and pass it to the tool call. But I think the point of other comments is that the MCP protocol is kinda clueless about how to standardize that within the protocol itself.

arscan 1y ago
I think an important thing to note is the MCP client is a distinct thing from the ‘LLM’ architecturally, though many LLM providers also have MCP client implementations (via their chat ui or desktop / cli implementations). In general, I’d say it’s not a good idea to pass bearer tokens to the LLM provider and keep that to the MCP client. But your client has to be interoperable with the MCP server at the auth level, which is flakey at the moment across the ecosystem of generic MCP clients and servers as noted.

cyberax 1y ago

> but should be possible when calling an LLM through an API style call, right (if you add additional pass thru headers Nope. I assumed as much and even implemented the bearer token authentication in the MCP server that I wanted to expose. Then I tried to connect it to ChatGPT, and it turns out to NOT be supported at all. Your options are either no authentication whatsoever or OAuth with dynamic client registration. Claude at least allows the static OAuth registration (you supply client_id and client_secret).