Add custom headers for HTTP/SSE transports

[alejoborbo]

Is your feature request related to a problem? Please describe.

Some of our MCP server requires authentication using API/APP keys passed by the HTTP headers.

Describe the solution you'd like

It might be great to have a way to enter a list of custom headers in the UI.

Describe alternatives you've considered

NA

Additional context

We are developing an MCP server, and this one requires authentication. For simplicity during the development, we are using a pair of API/APP keys (In the future, we'd like to rely only on OAuth2.0).

But headers can be used for other use cases than authentication, and might be useful for other people too :)

[alejoborbo]

If this demand makes sense, I'm happy to work on it 😊

[Jeetulsamaiya]

I ran into the same limitation and raised a similar feature request here: #750

To solve it, I’ve submitted a PR that adds support for multiple custom headers in the Inspector UI: #751

Your use case with API/APP keys aligns well with the broader need we identified (multi-tenant headers, environment headers, API gateways, etc.). Hopefully this PR can cover both our scenarios and make Inspector more flexible for real-world development/debugging.

[alejoborbo]

Thanks for pointing that out, I haven't seen this issue. Let me close this one in favor of your issue.

[alejoborbo]

Thank you @Jeetulsamaiya for looking into this. I really think that will make the inspector more flexible for general use cases 🤓

[Jeetulsamaiya]

Thanks @alex210501 🙌 Glad it helps your use case too! Feel free to drop any feedback on PR #751 🤓