Claude Duet review briefs cost $0.0243/mo, tests show

Duet sits in a cluster of proactive assistants that arrived in late 2026. Anthropic published it on 2026-10-21, CNBC framed it as a rival to OpenAI's dots and Meta's Muse, and the X announcement opened the waitlist to US Pro and Max users. The plan names then shifted: on 2026-10-30 Anthropic renamed Max 5x to Max and Max 20x to Ultra, keeping the $100 and $200 prices, so the Pro, Max and Ultra wording on the help page is a rename rather than a widening of access.

The practical argument is about volume, not features. Pulling the latest 50 Google reviews from each of the three shops showed review activity spread thin — 7, 8 and 4 days with new reviews in 90 — which is why the prompt tells Duet to stay silent when a since-dated call returns count 0. The billing test backs this up: an empty result cost $0, with the response listing empty_result_refunded, while a call that returned 2 reviews cost $0.001389 either way, so a limit of 20 adds no charge. The same data suggests the owner_response field may matter more than star ratings, since Flitch Coffee's last reply was on May 31 and its September two-star reviews went unanswered.

It is also candid about what it could not verify. The authors did not have a Duet account, so the screens and flows are configuration examples, and the help pages contain no mention of custom connectors — the only direct evidence is one Reddit user's report. The authors' own MCP call at 00:24 returned an empty result and an immediate refund. For an owner weighing this, those limits are the reason to check the custom connector inside their own Duet before relying on it.