Vercel Connect upgrade: AI agents call external tools without handling credentials

Vercel announced in its September 24 changelog that Connect now supports TanStack AI: agents built with TanStack AI can call OAuth-protected MCP servers, with no credentials for developers to store or rotate.

A new @vercel/connect/tanstack-ai subpath exports connectMCPTransport, which takes a TanStack transport config and attaches a Connect-backed auth provider. The provider is called before every MCP request, so the token is always fresh.

One detail worth noting is where authorization failures surface: if the user has not granted access, createMCPClient fails with a consent challenge before the model runs, and developers can catch it with getConsentChallenge and redirect to Connect's consent URL; otherwise the error would reach the model as an error string rather than the user as a redirect. This is a vendor-reported product capability from Vercel's own changelog, with no independent usage data yet.