Benchmark Almanac

MARS-Bench

Seed2.0 Pro 85.6% leads since Feb 2026 Fading

Models handle long multi-turn dialogues built from play-by-play sports commentary. Tasks test ultra multi-turn, interactive multi-turn and cross-turn reasoning.

Accepted to EMNLP 2025 Findings. The scoring field is a guess from the abstract.

In the authors’ words

Large Language Models (LLMs), e.g. ChatGPT, have been widely adopted in real-world dialogue applications. However, LLMs' robustness, especially in handling long complex dialogue sessions, including frequent motivation transfer, sophisticated cross-turn dependency, is criticized all along. Nevertheless, no existing benchmarks can fully reflect these weaknesses. We present MARS-Bench, a Multi-turn Athletic Real-world Scenario Dialogue Benchmark, designed to remedy the gap. MARS-Bench is constructed from play-by-play text commentary so to feature realistic dialogues specifically designed to evaluate three critical aspects of multi-turn conversations: Ultra Multi-turn, Interactive Multi-turn, and Cross-turn Tasks. Extensive experiments on MARS-Bench also reveal that closed-source LLMs significantly outperform open-source alternatives, explicit reasoning significantly boosts LLMs' robustness on handling long complex dialogue sessions, and LLMs indeed face significant challenges when handling motivation transfer and sophisticated cross-turn dependency. Moreover, we provide mechanistic interpretability on how attention sinks due to special tokens lead to LLMs' performance degradation when handling long complex dialogue sessions based on attention visualization experiment in Qwen2.5-7B-Instruction.

Abstract of MARS-Bench: A Multi-turn Athletic Real-world Scenario Benchmark for Dialogue Evaluation (arXiv:2505.23810, CC0)
Made by ByteDance Seed and collaborators (Yang et al.) Released May 2025 Multi-turn conversation Last in a launch post Feb 2026 , dropped after it saturated Last model added Mar 2026
Level
Everyday Most adults, without training
Scored
Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
Answers
Short answer A number, word or short string matched to a key.
2
Models scored in lab cards
2
Launch posts list it, from 1 lab
2
System cards report it, from 1 lab

Seed2.0 Pro leads with 85.6%

Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.

  1. 1 Seed2.0 Pro 85.6%
  2. 2 Seed1.8 70.1%
#ModelScoreSettingDateSource
1 Seed2.0 Pro 85.6% Feb 2026 Model card
2 Seed1.8 70.1% Dec 2025 Model card

2 models have held number one since its release in May 2025

Lab claims count from the day the card came out, independent runs from the model’s release.

ByteDance Seed
Lab claims Passed 85% in Feb 2026, by Seed2.0 Pro
Seed2.0 Pro 85.6%

The best score passed 85% in Feb 2026

All the scores we have, one dot each, so a model tested at several settings appears more than once.

Reported by the lab in its model card Best so far
0% 20% 40% 60% 80% 100% 2026 Near the ceiling (85%) Seed2.0 Pro Seed1.8 0% 20% 40% 60% 80% 100% 2026 Near the ceiling (85%) Seed2.0 Pro Seed1.8

Labs headline it less often now, last in Feb 2026

Launch posts from every lab that has listed it, one tick per post. Tall colored ticks include it, and short gray ones leave it out.

ByteDance Seed
DateLaunch postScoreAs the post writes it
14 Feb 2026 Seed2.0 Pro 85.6 MARS-Bench
18 Dec 2025 Seed1.8 70.1 MARS-Bench

2 system cards report it, from 1 lab

Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.

DateDocumentScoreAs the document writes itSection
21 Mar 2026 Seed1.8 model card 70.1 MARS-Bench (Table 1) Capabilities
14 Feb 2026 Seed2.0 Pro model card 85.6 MARS-Bench (Table 3) Capabilities

More in Instructions and chat

All 76 in Instructions and chat
  • IFEval In use Models answer about 500 prompts containing verifiable instructions such as word limits or required keywords. Code checks each instruction for strict and loose accuracy. Gemma 4 31B IT 98.9%
  • IFBench In use 58 new out-of-domain verifiable output constraints. Scored by programmatic constraint checks (strict or loose). Nemotron-Cascade 2 30B-A3B 82.9%
  • MultiChallenge In use Multi-turn conversations testing instruction retention, inference memory, versioned editing and self-coherence. Graded by LLM judge with rubrics. GPT-6.1 Sol 82%
  • Multi-IF In use Models follow verifiable instructions over three-turn conversations in eight languages, extending IFEval. Scored by instruction accuracy at each turn. LFM3-1.7B 89.1%
  • AdvancedIF In use Models respond to over 1,600 prompts with complex, multi-turn, and system-level instructions. A judge model checks each response against expert-written rubrics. MAI-Thinking-1 85%
  • IFStruct In use Models generate JSON or YAML that must follow a requested schema and phrasing constraints, without constrained decoding. A response passes only if every structural constraint holds. LFM3-1.7B 93.7%