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Measuring AI Ability to Complete Long Software Tasks

Thomas Kwa, Ben West, Joel Becker

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Amy Deng, Katharyn Garcia, Max Hasin, Sami Jawhar, Megan Kinniment, Nate Rush, Sydney Von Arx, Ryan Bloom, Thomas Broadley, Haoxing Du, Brian Goodrich, Nikola Jurkovic, Luke Harold Miles, Seraphina Nix, Tao Lin, Chris Painter, Neev Parikh, David Rein, Lucas Jun Koba Sato, Hjalmar Wijk, Daniel M. Ziegler, Elizabeth Barnes, Lawrence Chan

2025 · arXiv

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Despite rapid progress on AI benchmarks, the real-world meaning of benchmark performance remains unclear. To quantify the capabilities of AI systems in terms of human capabilities, we propose a new metric: 50%-task-completion time horizon. This is the time humans typically take to complete tasks that AI models can complete with 50% success rate. We first timed humans with relevant domain expertise on a combination of RE-Bench, HCAST, and 66 novel shorter tasks. On these tasks, current frontier AI models such as Claude 3.7 Sonnet have a 50% time horizon of around 50 minutes. Furthermore, frontier AI time horizon has been doubling approximately every seven months since 2019, though the trend may have accelerated in 2024. The increase in AI models' time horizons seems to be primarily driven by greater reliability and ability to adapt to mistakes, combined with better logical reasoning and tool use capabilities. We discuss the limitations of our results -- including their degree of external validity -- and the implications of increased autonomy for dangerous capabilities. If these results generalize to real-world software tasks, extrapolation of this trend predicts that within 5 years, AI systems will be capable of automating many software tasks that currently take humans a month.

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4 selected excerpts · 4 total mentions

ben_w
Neutral mention · rule
> Not misunderstanding. Then why did you write "Also, it’s super easy to game. Insert random lags, reduce tokens/sec, there you have a model that maintains attention over “long-time horizons”"? The time the LLM spends per task isn't the metric. How long you can leave the LLM alone, wall-clock time, without intervention, isn't "long-time horizons", it's more like "I gave it a list of tasks and it worked through them". Which is neat when it works, but different. > All I see now is celebration of how agents run for hours and handle “long-time horizons.” Yes? And? The long time horizons is with reference *to how long it would take humans to do*. Of course this is…
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celebrated. You're literally, on your opening sentence, complaining about 2 + 2 taking longer to solve, this isn't even close to the point of the metric. > How do you estimate the time it takes to complete a coding task in hours? If we had that formula, why have we been playing estimation poker or resorting to fibonacci series for predicting software tasks? Because you can’t. It’s a made up metric. Mostly it wasn't estimated, but rather measured: 2.2 Baselining In order to ground AI agent performance, we also measure the performance of multiple human “baseliners” on most tasks and recorded the duration of their attempts. In total, we use over 800 baselines totaling 2,529 hours, of which 558 baselines (286 successful) come from HCAST and RE-Bench, and 249 (236 successful) from the shorter SWAA tasks. 148 of the 169 tasks have human baselines, but we rely on researcher estimates for 21 tasks in HCAST. Our baseliners are skilled professionals in software engineering, machine learning, and cybersecurity, with the majority having attended world top-100 universities. They have an average of about 5 years of relevant experience, with software engineering baseliners having more experience than ML or cybersecurity baseliners. For more details about baselines, see Appendix C.1. - https://arxiv.org/html/2503.14499v3 As with all the other metrics, this is now basically saturated, as nobody seems to want to pay METR to hire a statistically significant number of engineers to spend 4h-1w on another 800 baselines. Or if they are, it's being kept very quiet.
falcor84
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Well, if you were to ask me, I would say that the biggest bottle-neck is the productive time horizon for AIs, which is currently at about 1h before SoTA agents go off-rails, based on the METR report[0]. As the report models, this time horizon doubles approximately every 7 months (R² = 0.98 on a log-scale), and thus if we assume that a CEO's work requires a time horizon of e.g. 10,000 hours to effectively plan and implement a long-term strategy, then we could expect companies to be able to replace CEOs by around 2033. There are of course other factors at play, but knowing companies' propensity to move fast and break things, I would indeed put some money that by the end of 2033, we'll see at least one mid-sized tech company delegate most (if not all) of its CEO decision-making to an AI agent. [0] https://arxiv.org/pdf/2503.14499
namaria
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As usual with these bombastic blog posts, you have to follow the paper trail to find the caveats that deflate the whole thing. From the papers about the tasks used in this estimation, we can easily find out that: LLMs never exceed 20% success rate on tasks taking more than 4h: HCAST: Human-Calibrated Autonomy Software Tasks https://metr.org/hcast.pdf LLMs hit a score ceiling at around 1-2h mark; LLM performance drops off steeply with increase in LOC count, never breaching 50% success rate after 800 lines and below 40% at the longest one at ~1600 lines. RE-Bench: Evaluating frontier AI R&D capabilities of language model agents against human experts…
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https://arxiv.org/pdf/2411.15114 And from the METR paper itself, only one model exceeds the 30 min "human task length" with 50% success, reaching that rate at 59 min "human task length", and at 80% no models but one can go over 4 min and one gets to 15 min "human task length" at that rate. It goes on to talk about extrapolating from this SOTA 59 min "time horizon" to ~168h, arguing that this is about one month of full time work and models that could breach 50% success rates at that time span could be considered transformative because they "would necessarily exceed human performance both at tasks including writing large software applications or founding startups (clearly economically valuable), and including novel scientific discoveries." Now despite the fact that "The mean messiness score amongst HCAST and RE-Bench tasks is 3.2/16. None of these tasks have a messiness score above 8/16. For comparison, a task like ’write a good research paper’ would score between 9/16 and 15/16, depending on the specifics of the task." But according to the METR paper, on the 22 '50% most messy' >1h tasks no model even breaches 20% success rates. And that is for tasks above "messiness = 3.0" on a set of tasks that goes to 3.2 "messiness". So there is absolutely no record of LLMs exceeding 50% success rates above 3.0 messiness ratings 1h long tasks but they are happy to claim that they see a trend towards 50% success rates at 168h long tasks approaching 9-15/16 messiness ratings? That's even assuming that their own estimate for the messiness of 'writing a good research paper' tops the chart is comparable to 'novel scientific discoveries', or 'writing large software applications or founding startups', which would seem to be many times messier than 'writing a good research paper', let alone doable in one month. Measuring AI Ability to Complete Long Tasks https://arxiv.org/pdf/2503.14499 So let's talk about the blog post claims that are not backed by the contents in these papers: "Claude 3.7 could complete tasks at the end of February 2025 that would take a professional software engineer about one hour." This is incredibly misleading. Claude 3.7 is the only model that was able to achieve a 50% success rate on tasks that are estimated to take humans at least 1h to complete. We should note that the METR paper also shows that for the 50% "messier" tasks no model even breaches 20% success rate. It should be noted that the HCAST set of tasks has 189 tasks of which only 45 breach 1h baseline estimates. The METR paper uses a 'subset' of HCAST tasks but it is not clear which ones and what the baseline time cost estimates for these look like. "o3 gives us a chance to test these projections. We can see this curve is still on trend, if not going faster than expected" This was a rushed evaluation conducted on a set of tasks that is different from that in the original paper, making the comparison between datasets spurious. Also, this seems relevant: "For the HCAST tasks, the main resource constraint is in the form of a token budget which is set to a high enough number that we do not expect it to be a limiting factor to the agent’s performance. For our basic agent scaffold, this budget is 2 million tokens across input and output (including reasoning) tokens. For the token-hungry scaffolds used with o1 this budget is 8 million tokens. For o3 and o4-mini, which used the same scaffold as o1 but did not support generating multiple completions in a single request, this budget is 16 million tokens." https://metr.github.io/autonomy-evals-guide/openai-o3-report... Back to the blog post: "We can actually attempt to use the METR paper to try to derive AGI timelines using the following equation: days until AGI = log2({AGI task length} / {Starting task length}) * {doubling time}" To find numbers to plug there, it makes some assumptions like "1h45 upper bound seems low let's boost by 1.5x" and then "but real world is messy so let's just divide the time by 10" which flies in the face of the fact that for tasks above messiness of 3/15 the models never breach 20% success rates. And considering the whole task set goes to 3.2/15 messiness score, that means that anything above that is a null data point. So this "Let’s assume true AGI tasks are 10x harder" assumption alone should drive "task length" to zero. "Additionally, we likely need more than 50% reliability. Let’s assume we need 80% reliability, which adds a 4x penalty, plunging starting task length down further to 3min45sec." At 80% reliability, only 2 models breach 4 minutes, with the best one approaching 15 minutes. And that is at messiness score of at most 3.2. But the best model regresses from the 2 bellow it on the overall estimation, and none breach even 20% reliability above that. So none of the modelling is valid, but the sleight of hand is offering the AGI formula and the 168h task length value for 'AGI' which of course is spurious because we're than talking about an AGI that cannot do any task messier than a 3.2/15, and a doubling rate of 3 to 7 months, we are stuck with accepting AGI is at most 10 years away as the blog post claims. But at most we can expect models that can do a few hundred lines of code edition at a 50% reliability rate on projects that would take around a month. And the METR paper has it's own projection of a "1-month AI" (which it never claims to be AGI) with 50% chance between end of 2027 and early 2028. So let me know if you have any 1 month projects under 800 LOC that you may need, with a 50% chance to be able to use an LLM to have a 50% shot at eventually getting it right, in about 2-3 years!
ben_w
Neutral mention · rule
Sure, but also the METR study showed the rate of change is t doubles every 7 months where t ~= «duration of human time needed to complete a task, such that SOTA AI can complete same with 50% success»: https://arxiv.org/pdf/2503.14499 I don't know how long that exponential will continue for, and I have my suspicions that it stops before week-long tasks, but that's the trend-line we're on.

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