If client has registered oauth client, but server can't find client id, re-register?

[irvinebroque]

The issue is that my local Cloudflare worker has a registered client for Cursor, and then I delete the .wrangler directory, which includes the KV store. Now, Cursor thinks that it's already registered, but that registration has disappeared.

[kentcdodds]

I think this may be more appropriate to be on https://github.com/cloudflare/workers-oauth-provider

The solution is either:

1. Respond in such a way that the client attempts to re-register
2. Dynamically register any client for which an ID is not found

I tried to do the second myself, but creating a new client with OAuthHelpers ignores the client ID I pass and creates a new client with a new ID.

[kentcdodds]

Here's a repository you can play with: https://github.com/epicweb-dev/epic-me-mcp

[geelen]

@kentcdodds you are using mcp-remote with Cursor (& others) correct? Cause the workaround is to just rm -rf ~/.mcp-auth which will give your clients a clean slate and they'll re-register. In this setup, mcp-remote is the client, so you need to clear its memory (not Cursor's).

I think the solution actually needs to land in the typescript SDK, as that's where the logic is: it needs to detect that its client ID is no longer valid and delete it before retrying. These are the current methods you need to implement to make a client like mcp-remote:

export interface OAuthClientProvider {
    get redirectUrl(): string | URL;
    get clientMetadata(): OAuthClientMetadata;
    clientInformation(): OAuthClientInformation | undefined | Promise<OAuthClientInformation | undefined>;
    saveClientInformation?(clientInformation: OAuthClientInformationFull): void | Promise<void>;
    tokens(): OAuthTokens | undefined | Promise<OAuthTokens | undefined>;
    saveTokens(tokens: OAuthTokens): void | Promise<void>;
    redirectToAuthorization(authorizationUrl: URL): void | Promise<void>;
    saveCodeVerifier(codeVerifier: string): void | Promise<void>;
    codeVerifier(): string | Promise<string>;
}

I think there needs to be something like:

invalidateAuthData(specifier: 'all' | 'client-registration' | 'tokens' | 'code-verifier'): Promise<void>

wdyt?

[geelen]

Btw there's a bit of a refactoring happening in #32, so use mcp-remote@next to be testing the latest. Hoped to cut a final release today but still testing

[kentcdodds]

Removing the mcp-auth directory worked for the mcp-remote usage. Thanks!

Good heads up on the refactoring going on.

Regarding where the solution is, I think each client needs to implement 401 handling and specifically "Invalid Client" error handling to trigger re-registration. I'm not certain whether this belongs in the OAuth Spec (or maybe it's already a part of the spec) or in the MCP spec, but it's more than just the TS client I think.

[jimaek]

We're running into the same issue with our remote MCP. Based on Cloudflare but the issue seems to be with this project. Especially on Claude desktop where deleting files is not possible

[adityakeka]

ended up with the same error, I think we should be able to register the client again if a 401 is received, because some servers can invalidate clients after a while as well.
When working through claude even if I reconfigure the server it doesn't try to register again because the URL mapping must be in the mcp-remote tool?

[geelen]

I have finally, finally made some progress on this. See #96 for more info, but it needed upstream changes and they've been raised in modelcontextprotocol/typescript-sdk#570

Please start using https://pkg.pr.new/mcp-remote@96 for testing though! It works a lot better, and I'll keep it updated while the upstream PR is in progress.

[kentcdodds]

@dcramer 👆

[jiashengguo]

I have finally, finally made some progress on this. See #96 for more info, but it needed upstream changes and they've been raised in modelcontextprotocol/typescript-sdk#570

Please start using https://pkg.pr.new/mcp-remote@96 for testing though! It works a lot better, and I'll keep it updated while the upstream PR is in progress.

@geelen Thanks for working on it, hope it can be merged soon! Met the same error when using GitHub Copilot.

[geelen]

Released as v0.1.14. Let me know how you get on!