Hey, thanks for the detailed report. This is a known CLI limitation, not something specific to Robinhood.
What’s happening:
The CLI uses the loopback redirect URI http://localhost:8787/callback, while the IDE uses a different callback mechanism, a deeplink like cursor://.... Robinhood’s OAuth server accepts the IDE option, but rejects the CLI loopback one. That’s why you see a 403 on authorize and a redirect to robinhood.com/oauth/error. So the same server can log in from the IDE, but fails via agent mcp login.
We saw the exact same pattern with Slack MCP in the CLI. Details here: Slack MCP: CLI login fails — redirect_uri mismatch (localhost:8787). Some fixes around redirect URI reordering have already shipped, but for providers that don’t allowlist loopback addresses, this still happens. This is a known issue and it’s being tracked, but I can’t share an ETA for Robinhood.
What you can do right now:
- The IDE path still works, auth for this server succeeds there.
- If Robinhood supports MCP via stdio or a token flow without an OAuth redirect, that transport is stable in the CLI since it fully avoids the loopback flow.
If I have an update on a fix, I’ll post it in the thread.