[Bug/Documentation Improvement] - How to pass authentication context into tool calls

[alexander-zuev]

Hi,

Context

• I am working on a Cloudflare Worker-based MCP which natively provides authentication context through it's own McpAgent this.props. This is obviously super useful for implementing user-based logic in tool calls.
• What I want is a clean way to access this info during tool calls, I have read the docs but could find anything remotely relevant in this regard
• RequestHandlerExtra has a conveniently named AuthInfo which is empty (perhaps it's not set by the workers oauth provider and should be set manually (?)

Question:

1. Is there an intended clean way to pass auth context to tool calls?
2. How would you recommend this is done?

I am currently passing the props directly into tool handler which obviously breaks it interface

 for (const tool of allTools) {
            console.log(`Registering tool: ${tool.name}`);
            this.server.tool(tool.name, tool.description, tool.paramsSchema, (params, extra) => {
                return tool.handler(params, extra, this.props);
            });

Am I doing something wrong?

[its-nikhil]

does #399 PR address this issue?

[alexander-zuev]

I can test - but looks like it? I am not sure workers oauth provider library would do that by default (or does it), but seems like it - @its-nikhil

[pcan]

Hi @alexander-zuev, did you manage to make Cloudflare McpAgent work with authInfo? I'm using this.props too, and after looking at the McpAgent source code, it seems there's no way to hook into the invocation of the tool callback to set authInfo 😢

[alexander-zuev]

Yep, I think they've (SDK devs) actually added a direct way to hook into auth context - I think I have seen it buried somewhere in the release notes.

Otherwise feel free to check out my source code to see how I've done it https://github.com/alexander-zuev/kollektiv-mcp

If I recall I modified the extra interface which is passed with every tool call, but since I did this recently I distinctly remember that I've seen somewhere in SDK notes that there is a more natural way to do that

My approach is not ideal since I had to modify the types which led to a lot of mortal kombat with TS errors