You'll notice
Pasting a redirect URL during MCP server sign-in is now checked against the expected value before it's accepted
What
Some browsers show a connection error during sign-in to an MCP server (a connector that gives Claude Code access to an external tool or service), so Claude Code lets you manually paste the redirect URL instead. Now, whatever you paste is checked against the URL that sign-in actually expects. If it doesn't match, you get an inline error saying "That isn't this sign-in's redirect URL" instead of the app silently accepting it.
Why
Previously any pasted text was accepted, which could let a wrong or mistyped URL through and break the sign-in silently. Validating the paste catches mistakes immediately.