Benchmark Almanac

FDE-Gym

Claude Opus 5.5 0.56 leads since October 2026
Not in model cards

Agents act as forward-deployed engineers in live customer systems, talking to scripted stakeholders to find unstated constraints. Score is the uplift on the customer's own success metric, from 0 to the reference solution's 1.

95 tasks from 20 real delivery projects in 18 sectors, the originals plus fact-altered variants. Stakeholder messages, trial runs and waiting cost points. A task resolves at 0.8 or more with no incident.

Released
October 2026
Kind
Building whole projects
Level
Expert
Scored
Checked automatically
Answers
Agent task
Tasks
All public
Strongest model tested
GPT-6 Astra #3 on the capability index
Last model added
September 2026
Scores refreshed
November 12th, 2026

In the authors’ words

Existing agent benchmarks typically evaluate agents on well-specified tasks defined by issue reports, specifications, or task tickets. Real-world customer delivery is different: forward-deployed engineers (FDEs) must clarify ambiguous requirements, work in live systems, and uncover unstated constraints. We introduce FDE-Gym, a benchmark of 95 end-to-end delivery tasks from 20 customer scenarios across 18 sectors, each adapted by industry experts from real-world delivery projects. In simulated customer environments with scripted stakeholders and modifiable customer systems, agents interact with stakeholders and operate on production-like systems to deliver working solutions. FDE-Gym scores a delivery by how much it improves the customer's own success metric, normalized between 0 (unchanged system) and 1 (reference solution), with penalties for stakeholder interactions (messages, trial runs, and waiting time). An online platform lets humans practice FDE skills under the same grading criteria. We evaluate 13 model configurations from seven providers. In the realistic setting, where unstated constraints must be discovered, the best configuration achieves a mean FDE-Gym score of 0.56 and resolves only 14 of the 95 tasks (a score of at least 0.8 with no incident). Discovering unstated constraints is the primary bottleneck: performance drops sharply when models must uncover them without explicit guidance. Yet information discovery alone does not account for the gap: even on the 23 tasks where the best configuration obtains every key fact from stakeholders, it reaches a normalized business uplift of 0.8 or above on only 10. These results reveal a substantial gap between solving well-specified tasks and delivering effective AI systems for real customers.

Abstract of FDE-Gym: The Last Mile of AI Delivery (arXiv:2610.22350, CC0)
12
Models scored on its own leaderboard

Claude Opus 5.5 leads with 0.56 among models released by September 2026

Best score per model from the benchmark's own leaderboard, read on November 12th, 2026. Where a model ran with several settings or harnesses, we keep its best.

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:

  1. 1 Claude Opus 5.5 0.56
  2. 2 Claude Sonnet 5.5 0.49
  3. 3 GPT-6 Astra 0.38
  4. 4 GPT-6.1 Sol 0.37
  5. 5 GLM-5.3-Flash 0.22
  6. 6 DeepSeek V4.1 Flash 0.21
  7. 7 Gemini 3.8 Flash 0.19
  8. 8 Qwen3.8 Flash 0.07
  9. 9 GPT-5.5 0.03
  10. 10 GPT-6 Luna -0.12
  11. 11 Mistral Small 4 -0.32
  12. 12 Claude Haiku 4.5 -0.33

Source: Official FDE-Gym leaderboard

#ModelScoreSettingDateSource
1 Claude Opus 5.5 0.56 Sep 2026 Official leaderboard
2 Claude Sonnet 5.5 0.49 Sep 2026 Official leaderboard
3 GPT-6 Astra 0.38 Sep 2026 Official leaderboard
4 GPT-6.1 Sol 0.37 Sep 2026 Official leaderboard
5 GLM-5.3-Flash 0.22 Aug 2026 Official leaderboard
6 DeepSeek V4.1 Flash 0.21 Sep 2026 Official leaderboard
7 Gemini 3.8 Flash 0.19 Sep 2026 Official leaderboard
8 Qwen3.8 Flash 0.07 Aug 2026 Official leaderboard
9 GPT-5.5 0.03 Apr 2026 Official leaderboard
10 GPT-6 Luna -0.12 Sep 2026 Official leaderboard
11 Mistral Small 4 -0.32 Mar 2026 Official leaderboard
12 Claude Haiku 4.5 -0.33 Oct 2025 Official leaderboard

Number one over time

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

Anthropic
Own leaderboard 1 leader

Source: Official FDE-Gym leaderboard

Scores over time

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

On the benchmark’s own leaderboard
-0.40 -0.20 0.00 0.20 0.40 0.60 2026 -0.40 -0.20 0.00 0.20 0.40 0.60 2026

Source: Official FDE-Gym 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.

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