What
A new complete_authentication tool for MCP servers that enables completing OAuth authorization flows directly within Claude Code, particularly useful in remote/SSH sessions where browser redirects don't work.
Usage
When an MCP server requires OAuth authentication, Claude can now call the authenticate tool to start the flow, then use complete_authentication with the callback URL the user pastes from their browser's address bar.
Details
- Handles the full OAuth callback flow: validates the URL contains an authorization code, resolves the pending auth promise, and reports success or failure
- Provides clear error messages when no OAuth flow is in progress, the callback URL is malformed, or authentication fails
- Specifically designed for remote sessions where
http://localhost:<port>/callbackpages fail to load but the URL in the address bar is still valid
Evidence
MCP OAuth completion handler (search for "Complete an in-progress OAuth flow for the")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.