τ-bench 2.0
Agents serve simulated customers in airline, retail, telecom and banking domains in six languages, by text or voice. Release 2.0 adds frozen task manifests and an intake domain for entity capture.
Sierra says 2.0 scores are not comparable with 1.x. The user simulator moved to GPT-5.5 and communication checks became LLM-judged. Languages are en, es, pt, hi, zh and ko.
- Made by
- Sierra
- Released
- October 2026
- Kind
- Customer service
- Level
- University
- Scored
- Checked automatically
- Answers
- Agent task
- Tasks
- All public
- Last model added
- October 2026
- Scores refreshed
- November 12th, 2026
Ava Zero tops the leaderboard with 86%
Best score per entry from the benchmark's own leaderboard, read on November 12th, 2026. Where a model ran with several settings or harnesses, we keep its best. Names in gray aren't in our model list: fine-tunes, agent systems, products and older models. They don't count toward leaders. The best model we track is GPT-Live-1, at 79.9%.
The newest model with a score here came out in September 2026, and nobody has tested a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:
- Claude Fable 5.2
-
Gemini 4 Carbon - Claude Opus 5.5
- GPT-6.1 Sol
- and 16 more
- 1 Ava Zero 86%
- 2 phonic-1 high 83.2%
- 3 GPT-Live-1 medium 79.9%
- 4 Grok Voice 2.0 high 71.4%
- 5 Gemini 3.8 Live Extended Thinking high 68.5%
Source: Official τ-bench 2.0 leaderboard
| # | Entry | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | Ava Zero | 86% | avartha_pipecat | Oct 2026 | Official leaderboard |
| 2 | phonic-1 | 83.2% | high, phonic | Oct 2026 | Official leaderboard |
| 3 | GPT-Live-1 | 79.9% | medium, openai_live | Oct 2026 | Official leaderboard |
| 4 | Grok Voice 2.0 | 71.4% | high, xai | Jul 2026 | Official leaderboard |
| 5 | Gemini 3.8 Live Extended Thinking | 68.5% | high, gemini | Sep 2026 | Official leaderboard |
2 models have held number one on the official leaderboard since its release in October 2026
Lab claims count from the day the card came out, independent runs from the model’s release.
Source: Official τ-bench 2.0 leaderboard
Scores over time
All the scores we have, one dot each, so a model tested at several settings appears more than once.
Source: Official τ-bench 2.0 leaderboard
No lab model card reports it yet
We read the headline results of 522 launch posts from 52 labs, and none of them list this benchmark.
Versions
We switch the top row to each new version when it comes out. Open it for one row per version. An old version stays in play while people still test it, so whoever first takes it past 85% gets credit for closing it out.
Sources: Official leaderboards and labs’ model cards
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