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How to Find the AI Benchmark You Actually Need

Thousands of benchmarks, no canonical index. How Benchmark Radar and the Lighteval Tasks Explorer help — and where they fall short.

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The prompt

The prompt that started this episode, as sent in (production notes for the hosts removed).

Podcast Prompt: Finding the Needle in the Benchmark Haystack — How Do You Discover AI Benchmarks?

There are thousands of AI benchmarks, ranging from famous evaluations like MMLU, HumanEval, and SWE-bench to a vast long tail of obscure, highly specialized benchmarks developed by academic researchers, independent developers, and AI labs.

But suppose you're trying to evaluate a model on something extremely specific. Perhaps you want to measure its ability to follow complex instructions, generate valid structured output, understand an unusual programming language, or perform a particular kind of reasoning.

How do you actually find out whether somebody has already built a benchmark for your use case?

The obvious starting point is Hugging Face, but even its enormous collection of datasets isn't necessarily easy to navigate when you're looking for a specific evaluation methodology rather than simply a dataset.

I'd like to explore the practical discipline of AI benchmark discovery.

Where should somebody begin searching? Beyond Hugging Face, what are the most useful benchmark directories, evaluation registries, academic indexes, GitHub repositories, and community resources? Are there specialized search engines or catalogs for benchmarks?

A couple of interesting resources to investigate:

- Benchmark Radar (https://benchmark-radar.org/about/) — a benchmark discovery engine associated with research published in September 2026. It aims to connect benchmark papers, code, datasets, and evaluation evidence. How does it work, how comprehensive is its coverage, and could it help discover obscure benchmarks? - Hugging Face Lighteval Tasks Explorer (https://openevals-open-benchmark-index.hf.space/) — a searchable index of evaluation tasks, including filtering by language and benchmark type. How does this differ from searching the ordinary Hugging Face dataset repository, and what are its limitations?

Let's also investigate Papers with Code and its successors or alternatives, academic search engines, GitHub topic indexes, evaluation frameworks such as EleutherAI's LM Evaluation Harness, and any emerging benchmark registries. Which of these are genuinely useful discovery tools, rather than simply collections of popular benchmarks?

How do you discover benchmarks buried in academic papers, particularly when their names don't clearly describe what they measure? Can you search by task, capability, evaluation methodology, or the models that have been tested against them?

Let's work through a realistic example: imagine we're developing a custom LLM router and want to benchmark its ability to select the most appropriate model for different types of prompts. How would we systematically investigate existing evaluations before deciding to develop our own?

There's also an important distinction between finding a benchmark and finding one that's actually usable. How do we determine whether its dataset is publicly available, its evaluation harness is maintained, its licensing permits our intended use, and its methodology is sufficiently documented to reproduce the results?

We should also consider benchmark quality. An evaluation might be discoverable but suffer from data contamination, poor task coverage, weak validation, or outdated assumptions. How do we distinguish an obscure but valuable benchmark from one that's obscure for good reason?

Finally, when should we conclude that a suitable benchmark simply doesn't exist? How exhaustive should our search be before we invest the effort in creating something ourselves?

The goal of this episode is to develop a practical, repeatable benchmark discovery workflow that AI developers, researchers, and independent model evaluators can use before reinventing the wheel. I'd particularly like us to identify concrete tools and search strategies that listeners can use immediately, including resources that aren't already widely known.

Benchmark discovery is harder than it looks, and the reason is lexical. Benchmark names are labels chosen to be distinctive, not informative — MuSR, Dyck Language, LegalSupport tell you nothing about what they measure until you read the paper. Hugging Face is a great place to find a dataset once you know its name, but its repository is organized around the artifact, not the capability, so you can't easily ask it for "benchmarks that measure structured output validity."

Two tools try to close that gap. Benchmark Radar, a living database and search engine published as a preprint in September, keeps discovery and catalog deliberately separate: a daily pipeline reads 37 sources over a rolling 48-hour window, while the catalog is built from four registered sources covering 1,283 records and 12,916 numeric score observations. Its core design rule — a number is only worth as much as the document it came from — means scores stay partitioned by reporting source and are never merged into a single ranking. Its taxonomy records interaction paradigm and modality as separate facets rather than cramming everything onto one axis, which matters: of 345 agentic records, only 128 take "Agentic and Tool Use" as their top-level class, while 117 sit under coding. Search is BM25F with field weighting, and results show which query words matched and which didn't. The authors are candid about limits: lexical matching misses paraphrases and renamed tasks, and the discovery side can't reliably classify capability.

The Lighteval Tasks Explorer is a different animal — a Hugging Face Space that renders Lighteval's task table as a searchable list, showing dataset IDs and exact harness invocation strings. That's the difference between "a dataset exists" and "this benchmark runs in a maintained harness, and here's how you call it." It surfaces the long tail — Kyrgyz Evals, Filipino Evals, German RAG Evals — that download counts would otherwise bury. But the original Space is currently in a runtime error state, fetching a 404 from the Lighteval main branch. The benchmark tooling ecosystem is held together with tape, and the tape degrades. Papers with Code, the canonical example, was retired by Meta in late July 2025 with no notice.

Sources

What the research for this episode read before the script was written. Primary sources first.

  1. Benchmark Radar about page primary
  2. Wu et al., Benchmark Radar, arXiv:2609.11115v3, revised 2026-09-22 primary
  3. Lighteval Tasks Explorer (mirror) primary
  4. Lighteval docs, v0.13.0 primary
  5. abstract page, submitted 2026-09-10
  6. Benchmark Radar v0.9.0 Technical Report, 2026-08-29
  7. repo, created 2026-07-27, MIT
  8. original Space, runtime error / HTTP 404
  9. CodeSOTA, Papers with Code shutdown record
  10. CodeSOTA about, launched 2025-12-10
  11. successor list thread
  12. preserved PWC data
  13. When AI Benchmarks Plateau, ICML 2026, v4 2026-08-06
  14. BenchMarker, ACL 2026
  15. Cross-Context Verification
  16. Excess Separability (withdrawn result)
  17. RouterBench
  18. RouterEval
  19. LLMRouterBench
  20. TwinRouterBench
  21. Agent-as-a-Router / CodeRouterBench
  22. LLMRouter / xRouteBench
  23. DSC benchmark, router fragility
  24. KATS, task-oriented dataset search

Mentions

  • Benchmark Radar Living benchmark database and search engine
  • CodeRouterBench Code routing benchmark comparing regret across models
  • Lighteval Hugging Face evaluation harness
  • Lighteval Tasks Explorer Searchable Hugging Face Space of Lighteval tasks
  • LLMRouterBench Routing benchmark with 33 models and baselines
  • LM Evaluation Harness Framework for property-based LLM evaluation
  • Papers with Code Retired paper-code-benchmark registry by Meta
  • RouterBench LLM routing benchmark from Martian and Berkeley
  • RouterEval Large-scale routing performance record benchmark
  • TwinRouterBench Step-level routing benchmark for agents

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Episode Book (PDF)

The episode's record — date, duration, models, sources — with the full transcript

#6051: How to Find the AI Benchmark You Actually Need

Corn
There are thousands of AI benchmarks. MMLU, HumanEval, SWE-bench, and then a long tail nobody has ever heard of. And if you need the one that measures your specific thing, you are looking for a needle in a haystack that keeps growing.
Herman
And the haystack has no index.
Corn
Right. Daniel's question is basically this. Suppose you want to evaluate a model on something narrow. Structured output validity, an unusual programming language, one kind of reasoning. How do you find out whether somebody already built the benchmark before you spend a month building your own? He wants the practical search discipline. Where to look past Hugging Face, which registries are useful, how to tell whether a benchmark you found is any good, and when to give up and build your own. He names two starting points, Benchmark Radar and the Hugging Face Lighteval Tasks Explorer, and he wants a worked example around a custom LLM router.
Herman
Good. Because the honest answer up front is that there is no canonical place to look. That is the uncomfortable truth.
Corn
Start there, then. Why is this hard? There are thousands of benchmarks.
Herman
It's hard because benchmark discovery is not really a search problem in the way people expect. It is a lexical problem wearing semantic clothing. Benchmark names don't describe what they measure. MuSR. Dyck Language. LegalSupport. You could read those three names a hundred times and not know that one is multistep reasoning in narratives, one is hierarchical reasoning over formal languages, and one is fine-grained legal reasoning by reverse entailment.
Corn
So the name is a label, not a description.
Herman
The name is a label chosen by whoever wrote the paper, usually to be distinctive rather than informative. That's fine for them and terrible for you, because the thing you can search on is the thing that least describes the content.
Corn
And Hugging Face doesn't fix that.
Herman
Hugging Face is the obvious starting point and it's a great place to find datasets. But its dataset repository is organized around the artifact, not the capability. You can find the dataset behind a benchmark if you already know its name. You cannot easily ask it for "benchmarks that measure structured output validity" or "benchmarks for unusual programming languages," because that isn't the unit it indexes.
Corn
It indexes what exists, not what it does.
Herman
And that's the gap the whole episode lives in. Two resources try to close it, and Daniel named both. Benchmark Radar, which is a living database and search engine published as a preprint in September. And the Lighteval Tasks Explorer, which is a window into one evaluation harness's task table. Both are more interesting than they look, and both are more limited than their marketing suggests.
Corn
So the arc is discovery tools, then the router, then usability, then when to stop searching.
Herman
And the punchline at the end of the router example is going to sting a little.
Corn
Good. Let's earn it. Hugging Face first, properly. Why is it a poor discovery tool, in concrete terms?
Herman
Because the search box matches text. If you type "router" into the Hugging Face dataset search you get datasets with router in the name or the card. What you want is "evaluations of a model's ability to select the right model for a prompt," and no field in that schema holds that. The organizational unit is the artifact. The capability lives in the prose of a paper, if anywhere.
Corn
So you can find the thing once you know its name, and you can't find its name by looking for the thing.
Herman
That's the whole disease. And it's why the interesting tools are the ones that index something other than the artifact. Benchmark Radar indexes benchmark records with their evidence attached. The Lighteval Explorer indexes harness tasks. Both are answering a different question than Hugging Face is.
Corn
Take Benchmark Radar first. What is it actually?
Herman
A collector and a catalog, kept deliberately separate. The daily discovery pipeline reads arXiv, GitHub, Hugging Face, OpenReview, Semantic Scholar, Hacker News and the labs' own release feeds over a rolling forty-eight hour window. Thirty-seven sources in total, thirteen direct connectors and twenty-four first-party research and engineering feeds.
Corn
And the catalog?
Herman
Built from four registered sources. LLM Stats, OpenCompass Hub, Artificial Analysis, and the evaluation tables labs publish with a model. That's one thousand two hundred and eighty-three source records. The coverage census shows twelve thousand nine hundred and sixteen numeric score observations across seven hundred and ninety records. Four hundred and ninety-three records have no numeric score at all, but four hundred and sixty-four of those still link to a paper, a repo or a dataset.
Corn
So a third of the catalog is unscored but still documented.
Herman
Which is the right way round. A benchmark with no scores yet is still a benchmark you might want. And the link counts bear that out. Four hundred and seventy-five records link to papers, five hundred and six to repositories, two hundred and ninety-three to datasets.
Corn
Now the design rule, because that's the part I find interesting.
Herman
"A number is only worth as much as the document it came from." Scores stay partitioned by the source that reported them. They are never merged into a single ranking, because those sources measure under different conditions and say so. And where a field is missing, the page leaves it out rather than filling it in.
Corn
A benchmark registry that refuses to rank.
Herman
Deliberately. It's a rebuke of leaderboard culture built into the architecture. If LLM Stats reports a score and a model report reports a different score on the same benchmark, Benchmark Radar shows you both, with the source attached, and does not average them.
Corn
I like that more than I expected to. What about the taxonomy?
Herman
This is the most interesting design decision in the whole system. One thousand two hundred and seventy-nine of the one thousand two hundred and eighty-three records are classified into eleven top-level domains and sixty-three sub-domains, using the publishers' own labels. But interaction paradigm and modality are recorded as separate facets rather than being crammed into the same axis.
Corn
Give me the example.
Herman
Of three hundred and forty-five agentic records, only one hundred and twenty-eight take "Agentic and Tool Use" as their Level 1 class. One hundred and seventeen sit under "Coding and Software Engineering." A single-axis scheme would have hidden those hundred and seventeen inside a coding bucket and you'd never find them when you went looking for agentic evaluations.
Corn
So the classification admits that a benchmark can be two things at once.
Herman
And that's most benchmarks. The flat category systems are the ones that lose things.
Corn
The search itself. Lexical?
Herman
BM25F with field weighting and boosts for name and phrase matches. Each result shows you which query words matched, which ones didn't, and the score components. That's unusually honest for a search box. If you search "structured output" and the word "structured" didn't match anything, it tells you.
Corn
Its authors admit what it misses.
Herman
In their own words, lexical matching can miss paraphrases and renamed tasks. Which is the exact failure the whole episode is about. If the benchmark is called LegalSupport and you searched for "legal reasoning," you need the word overlap to save you, and sometimes it doesn't.
Corn
There's a CLI.
Herman
There is. You initialise and sync, the archives are SHA-256 verified, and there's JSON output so you can pipe it. There's also an agent skill you can install if you want a coding agent to run the searches for you.
Corn
A benchmark registry with an install command. That's the most twenty twenty-six thing I've heard this week.
Herman
And the authors are honest about the limits. Retrieval precision, task suitability and time saved are not evaluated. The worked example in the paper has no controlled baseline. arXiv discovery doesn't backfill papers posted before the collection window. And task-capability classification remains unvalidated, because the CI null extractor assigns no capability levels to five thousand eight hundred and sixty-three discovery-derived tracks.
Corn
Say that last part plainly.
Herman
The discovery side finds a lot of artifacts, but it can't reliably tell you what capability each one tests. So the classification that makes the catalog useful is only trustworthy on the catalog side, the hand-curated and registered sources, not on the freshly discovered stuff.
Corn
Fresh discovery, unlabelled.
Herman
Fresh and unlabelled, but found. Which is still worth something when the alternative is not knowing it exists.
Corn
One more thing from the paper before we move. The prior-art search.
Herman
A contributor used the CLI plus ordinary web search to assemble a five-row related-work table on credit assignment in agentic training, each row with arXiv and GitHub links, to check whether a proposed evaluation duplicated existing work. That's the workflow in miniature. Search tool plus human judgement, used to answer one question: has somebody already done this?
Corn
And the answer was five papers.
Herman
Which is the recurring theme. Somebody has almost always already done it.
Corn
Now the Lighteval Tasks Explorer, because Daniel's right that it's a different animal.
Herman
Completely different. It's a Hugging Face Space by Guilherme Penedo, created in June of twenty twenty-four. It renders Lighteval's own task table as a searchable, filterable list. Free-text search over the task descriptions, language filters, a benchmark-type filter, and star markers for the recommended ones.
Corn
And the key difference from searching the dataset repo?
Herman
It tells you the harness invocation. Each entry shows the dataset IDs and the exact Lighteval task name. So you get gpqa, ifeval, ifbench_test, aime24_gpassk, bigbench_extra_hard, long_horizon_execution. That's the string you put in the command. That is not just "a dataset exists." That is "this benchmark runs in a maintained harness, and here is how you call it."
Corn
Which matters enormously, and we'll come back to that in the usability section.
Herman
It's a preview of the whole quality argument. If a benchmark is implemented in a maintained harness, that's half the usability question answered before you've read the paper.
Corn
And it surfaces the long tail.
Herman
That's the other virtue. Alongside GPQA and IFEval and Humanity's Last Exam, it has Dyck Language, Entity Data Matching, LegalSupport, MuSR, MultiChallenge, Long-Horizon-Execution. Kyrgyz Evals. Filipino Evals. German RAG Evals. Some of these you would simply never encounter by browsing the dataset repository, because they don't have the download numbers to surface.
Corn
And yet.
Herman
And yet. The original Space is currently in a runtime error state. Its app fetches the task table from the Lighteval main branch and gets a four oh four. The file has moved or been renamed. The mirror URL still serves content, but its freshness relative to the current task table is unverified.
Corn
A tool built in June of twenty twenty-four is already broken on its own data file.
Herman
Which is not a knock on the person who built it as a volunteer Space. It's a fact about the infrastructure. The benchmark tooling ecosystem is held together with tape, and the tape degrades.
Corn
Papers with Code.
Herman
The canonical example. Meta retired it in late July of twenty twenty-five with no notice. Users saw five oh two errors, and the domain now redirects to Hugging Face Trending Papers. At peak it indexed seventy-nine thousand eight hundred and seventeen papers, nine thousand three hundred and twenty-seven benchmarks, five thousand six hundred and twenty-eight datasets, across sixteen nested task areas.
Corn
And acquired it in twenty nineteen.
Herman
Pledging it would remain a neutral, open and free resource. Then it went offline in a day.
Corn
The archive survived.
Herman
The historical JSON survives frozen on GitHub under the Papers with Code data repo. Community mirrors exist, including one that preserves the evaluation tables with task hierarchies and SOTA metrics, and a Hugging Face archive. So the data is not lost. But there's no live registry behind it anymore, which means you're searching a corpse.
Corn
There's a line from one of the successors about that. Read it.
Herman
"A seven-year archive of leaderboards, submissions and citations went offline without notice, and the field was briefly reminded that benchmark infrastructure, however load-bearing it felt, had been sitting on a single corporate hosting decision the whole time."
Corn
That's the sentence. That's the whole maintenance problem in one breath.
Herman
And the successors have not consolidated. Hugging Face Trending Papers is the official redirect, but no SOTA leaderboards. Then there's PapersWithCodePlus, OpenCodePapers, SOTAPapers, Catalyzex, ResearchLit, Hyper.ai, and CodeSOTA, which launched in December of twenty twenty-five and requires a frozen commit, a declared environment and a recorded seed for every submission, with dated and lineaged scores.
Corn
That's the most rigorous of the lot.
Herman
And CodeSOTA's own complaint is that none of the successors pointed at, Hugging Face Trending Papers, Semantic Scholar, Connected Papers, replicate the unified paper-code-benchmark-dataset-method linkage that Papers with Code had.
Corn
So it fragmented into pieces.
Herman
Into pieces, each of which covers part of the old whole, none of which covers all of it.
Corn
What about the academic search engines and the GitHub topic indexes?
Herman
Useful for finding papers, useless as registries. arXiv full-text search, Semantic Scholar, Google Scholar, all fine when you have a term to search. GitHub topics like benchmark or evaluation are noisy, but they do surface repos that never made it into a paper, which the academic indexes can't. Supplementary, not primary.
Corn
And the evaluation frameworks themselves?
Herman
LM Evaluation Harness from EleutherAI, Lighteval, HELM, OpenAI Evals. These are collections of implemented benchmarks, not discovery engines. But the hidden advantage is the one I mentioned. If a benchmark is implemented in a maintained harness, somebody has done the work of making it runnable. The Explorer is essentially a window into one of those harnesses.
Corn
So the honest verdict on the discovery landscape is that there is no dedicated benchmark search engine beyond Benchmark Radar.
Herman
The closest adjacent thing is a research prototype called KATS, a task-oriented dataset search system that builds a knowledge graph over scientific literature. But it searches datasets, not benchmarks, and it's a prototype.
Corn
And nobody has published a semantic benchmark search with reviewed relevance judgments.
Herman
Nobody. Which is a odd gap for a field this obsessed with measuring things.
Corn
That's the discovery landscape. Now make it concrete.
Herman
The router.
Corn
You're building a custom LLM router. It takes a prompt and picks the model most likely to handle it well. How do you systematically investigate whether evaluations already exist before you build your own?
Herman
You run the stack in order. Benchmark Radar first, because it's the widest catalog. Search "router," "routing," "model selection," "LLM router." Then the Lighteval Explorer, to see whether the harness has anything. Then arXiv full-text for "LLM router benchmark," "model routing evaluation." Then GitHub topics. Then the frozen Papers with Code archives and the successors. Five places, one afternoon if you're efficient.
Corn
And what do you find?
Herman
You find that the question has been answered at least six times, with increasing sophistication, over about two and a half years. RouterBench in March of twenty twenty-four, out of Martian and Kurt Keutzer's Berkeley lab. Over thirty thousand prompts and four hundred and five thousand inference outcomes from eleven models, drawn from MBPP, GSM8K, Winogrande, HellaSwag, MMLU, MT-Bench. Martian's framing was that it would do for routing what ImageNet did for computer vision.
Corn
Did it?
Herman
It gave everyone a common substrate to argue on, which is most of what ImageNet did. Then RouterEval, which built over two hundred million performance records for twelve evaluations across eight thousand five hundred models, and documented a model-level scaling phenomenon.
Corn
Two hundred million.
Herman
Then LLMRouterBench this January. Over four hundred thousand instances, twenty-one datasets, thirty-three models, ten routing baselines. And its finding is the one that should stop you in your tracks. "Several recent approaches, including commercial routers, fail to reliably outperform a simple baseline."
Corn
The commercial routers are losing to a baseline.
Herman
And the gap to Oracle is persistent, driven by model-recall failures. Which is a wonderful phrase. The router can't pick the right model when it doesn't remember that the right model is an option.
Corn
That's not a routing problem, that's a candidate-set problem.
Herman
That is exactly what it is. Then TwinRouterBench, revised at the end of September, which is step-level routing for agents. Static track of nine hundred and seventy router-visible prefixes from five hundred and twenty instances across SWE-bench, BFCL, mtRAG, QMSum and PinchBench, plus a dynamic track on the five-hundred-case SWE-bench Verified suite.
Corn
Step-level meaning the router decides mid-trajectory, not just at the start.
Herman
Mid-trajectory, which is where real agent systems actually make routing decisions. Then CodeRouterBench, around ten thousand task instances with verified scores from eight frontier models, comparing on regret across streaming tasks. And xRouteBench, which covers generic, memory-augmented, vision, time-series and personalized routing, and found learned routers beating the strongest fixed-model baseline by fourteen point six percent relatively.
Corn
Did you get all six?
Herman
Six. Plus a cautionary one. The DSC benchmark from twenty twenty-five showing routers make suboptimal, category-driven decisions. A BERT-based router sends all coding and math to the most powerful model, and routes jailbreak attempts to weaker models.
Corn
That's the security bug nobody asked for.
Herman
It's a model of routing as an optimization for quality that accidentally optimizes for safety lapses. If a router learns "hard-looking prompts go to the good model, weird-looking prompts go to the cheap model," it will route adversarial inputs to whatever has the least refusal behavior.
Corn
So the lesson from the router example is that the niche filled up in two and a half years.
Herman
And that a competent search finds all six in an afternoon. If you did not know where to look, you might build a seventh, worse, and defend it in a blog post.
Corn
Now the harder question. Finding a benchmark isn't finding a usable one.
Herman
And this is where most of the real work is. The usability checklist has four boxes and a benchmark has to clear all four. Dataset publicly available. Harness maintained. License permits your use. Methodology documented well enough to reproduce.
Corn
Take them one at a time. Dataset availability.
Herman
Where does the data actually live? If it's on Hugging Face, good. If it's in a GitHub repo, fine. If it's on a lab's own servers, ask what happens when the lab reorganizes. Papers with Code went offline in a day. A benchmark dataset on an institutional file server can do the same.
Corn
Harness maintenance.
Herman
Is the benchmark implemented in LM Evaluation Harness, Lighteval, HELM, or is it a one-off script in a repo that hasn't been touched since twenty twenty-three? If it's the latter, you are signing up to maintain that script yourself. It will break when the model API changes a response format, and it will be your weekend.
Corn
Licensing.
Herman
MIT, Apache two, CC-BY, or the phrase research only. That phrase kills commercial use and nobody reads it before they build a product against the benchmark.
Corn
Methodology documentation.
Herman
Can you reproduce the numbers from the paper? Or are there missing hyperparameters, prompt templates, scoring rules, the exact seed, the exact model version? If the paper reports a number and you cannot get within a point of it, the benchmark is not ready for you to use, whatever its other virtues.
Corn
Give me the maintenance example that lands, because I think people will remember this one.
Herman
The Lighteval Explorer itself. Built in June of twenty twenty-four, and by October of twenty twenty-six the original Space is four oh four on its own data file. If a tool built by a competent person to index benchmarks can break that quietly, a benchmark harness maintained by one grad student can break too, and nobody will tell you.
Corn
It's not a moral failing. It's a supply chain.
Herman
And the supply chain needs a fallback layer, which is the practical takeaway. Any workflow you build should assume the front doors are unreliable. Keep the frozen archives bookmarked. Keep the arXiv search habits. Keep a note of which harness you trust.
Corn
Now quality. How do you distinguish obscure-but-valuable from obscure-for-a-reason?
Herman
Four signals and a strong prior. The signals. Expert curation, because it correlates with survival. Recent publication, because older benchmarks saturate. Maintained harness, because a benchmark nobody maintains is a benchmark nobody trusts. And evidence of independent use, because a benchmark used by multiple unrelated groups has been stress-tested by strangers.
Corn
And the prior?
Herman
Fame is not a quality signal. That's the strong prior. The saturation finding is the strongest single piece of evidence for it. Across sixty language model benchmarks and fourteen saturation-related properties, nearly half exhibit saturation, with rates increasing with age. And resilience is driven by expert curation, not by keeping test data private.
Corn
Which is counterintuitive. The privacy instinct turns out not to be the thing that saves a benchmark.
Herman
The thing that saves a benchmark is somebody caring about it for a decade.
Corn
Contamination.
Herman
BenchMarker audited twelve multiple-choice question-answering benchmarks and found forty-seven percent of TruthfulQA appears online and one hundred percent of HellaSwag violates multiple writing rules. Contaminated items inflate accuracy. Writing errors lower it and change rankings. And prior repairs fixed their target flaw but added new ones.
Corn
Forty-seven percent of TruthfulQA is online.
Herman
And HellaSwag has never had a version where every question was clean. That's a benchmark that has been cited tens of thousands of times.
Corn
Then there's the counter-counter.
Herman
Cross-context verification claims thirty-three percent of prior contamination labels on SWE-bench Verified are false positives, and that contamination is binary, models either recall perfectly or not at all. So the field can't even agree on how contaminated its own flagship tests are.
Corn
And there was a paper that retracted its own result.
Herman
An activation-probing contamination detector that withdrew its own nominally significant result after finding its placebo baseline's variance exceeded the permutation null's. That's the healthiest thing in this whole discussion. A paper found a bug in its own methodology and said so.
Corn
So what does obscurity actually mean?
Herman
It means one of two things, and they look identical from the outside. Obscure because it's bad. Contaminated, poorly validated, outdated, one author, no maintainer. Or obscure because it's new and niche and nobody has cited it yet. The signals that separate them are curation, recency, maintenance, documentation and independent use, which is exactly the list we just gave.
Corn
Use the classifier again. If you're uncertain, what's the tiebreak?
Herman
The tiebreak is whether you can run it today. A benchmark you can run today, on data you can download, in a harness that works, with a scoring script you can read, is worth more than a famous benchmark you cannot reproduce. That's the tiebreak. Runnability beats reputation.
Corn
Now the final question. When do you stop searching and start building?
Herman
The bar for "doesn't exist" should be high. The router example sets it. A well-defined niche had six benchmarks in two and a half years. Most niches you think are empty are not empty. They're just not indexed in a way that your first search finds.
Corn
So how exhaustive does the search need to be?
Herman
Five places. Benchmark Radar. The Lighteval Explorer. arXiv full-text. GitHub topics. The frozen Papers with Code archives and the successors. If none of those turn up a benchmark that measures your specific capability, you can be reasonably confident none exists, or at least none that's discoverable, which for your purposes is the same thing.
Corn
Then the build-versus-buy.
Herman
Building your own is expensive. Dataset construction, validation, contamination checks, maintenance, and the thing nobody budgets for, which is external validation. A homegrown benchmark has no external credibility. Nobody will cite it. Nobody will trust its numbers. You will spend a year building the thing you could have used on day one if you had searched properly.
Corn
So the discovery workflow exists to prevent reinventing the wheel.
Herman
And to prevent building a worse wheel. That's the point. Reinvention is annoying. Worse reinvention is embarrassing.
Larry
Are you tired of searching for the right benchmark? Tired of opaque names, broken harnesses, and leaderboards that rank nothing? Now there's an answer. New from the makers of nothing in particular, DiscoverEval. DiscoverEval finds the perfect benchmark for your specific use case in under four seconds, using advanced lexical matching, semantic understanding, and a proprietary algorithm that we cannot describe for legal reasons. DiscoverEval has been shown in internal tests to identify benchmarks that exist, benchmarks that may exist, and benchmarks that should exist but do not yet, which DiscoverEval will generate for you as a downloadable CSV. Ask your doctor if DiscoverEval is right for you. Do not use DiscoverEval if you are allergic to DiscoverEval. Side effects may include mild optimism, involuntary leaderboard construction, the sudden belief that you have found the right benchmark when you have not, temporary blindness to data contamination, persistent numeric confidence, and in rare cases, the construction of a seventh router benchmark in a niche that already contains six. Tell your doctor if you experience an unexplained gap to Oracle, model-recall failure, or the sensation that a baseline is outperforming a commercial product you paid for. DiscoverEval is not right for everyone. Do not take DiscoverEval if you have ever trusted a leaderboard.
Corn
Where were we. Runnability beats reputation.
Herman
It does. And the other thing worth saying is that the discovery discipline is not a one-time task. It's a habit. You search before every build, not once in your career.
Corn
Say more about that.
Herman
The registry you used last year may not exist this year. Papers with Code went offline in a day. The Lighteval Explorer is broken today and may be fixed tomorrow. The benchmark you found last quarter may have saturated. So the workflow isn't a checklist you complete. It's a set of bookmarks and search habits you maintain.
Corn
What are the open questions, then? Not closing statements. Open questions.
Herman
Whether anyone will ever evaluate Benchmark Radar's retrieval accuracy. The authors are honest that they haven't. Somebody should. Whether the successor ecosystem to Papers with Code undergoes any consolidation, or whether it remains a fragmented set of partial replacements each claiming to be the one that matters. And whether anyone will build a semantic benchmark search with reviewed relevance judgments, which is the thing Benchmark Radar explicitly, deliberately, does not do.
Corn
Three open questions about the infrastructure and none about the benchmarks themselves.
Herman
Because the benchmarks keep arriving. It's the infrastructure that keeps dying.
Hilbert
"Lexical." You keep saying it. It's not lexical.
Corn
It's what the paper calls it.
Hilbert
The paper calls its own search lexical. The problem isn't lexical.
Corn
Alright. What is it.
Hilbert
The problem is that the only reliable index of what a benchmark measures is in the head of the person who built it. I know this because I spent eleven years indexing things nobody else wanted to index. Every benchmark I ever encountered got a card. Three hundred and forty of them.
Corn
Index cards. Paper.
Hilbert
Paper. With a rule down the middle, the benchmark name top left, the measure top right, and a short note at the bottom about whether the data was any good. Fourteen top-level categories of my own design. Plus one category called Miscellaneous, Do Not Ask. Sixteen cards in it. Fourteen benchmarks and two things that turned out to be datasets. I've thought about moving them. I haven't moved them.
Corn
And you've lost some.
Hilbert
Twelve. I know the exact number because I keep a card for each of them. In a separate section. Known Missing.
Corn
So there's a Known Missing section.
Hilbert
Twelve cards in it. Each one is a card describing a card that I can't find. Description, approximate date of last sighting, and a small sketch of what I remember the handwriting looking like.
Corn
Have you ever found any of them.
Hilbert
No. But I'm confident they're in the house.
Corn
Alright. And the fourteen categories. What are they.
Hilbert
That's where it gets tricky. The classification scheme requires a key. Forty pages. It's cross-referenced by category, sub-category, and a small set of priority flags I made up in the second year. I can't use the cards without the key.
Corn
Where's the key.
Hilbert
In the Known Missing section.
Corn
The key is one of the twelve missing cards.
Hilbert
It's not a card. It's a forty-page booklet. But it went into the Known Missing section because I couldn't find it, and the section accepts non-cards as long as they're missing.
Corn
You have an index you can't read.
Hilbert
I've been meaning to rewrite the key from memory. But I'm worried I'll get a category wrong and mis-file everything. It's better to leave the cards where they are than to move them into the wrong category.
Corn
How long have you been meaning to rewrite it.
Hilbert
A while. Since before the Explorer was built. I checked when the Explorer was built, actually, because I was going to mention that I've been stuck on this longer than it's existed.
Corn
And the digitization idea.
Hilbert
I've been considering it. It's the obvious solution. I could put everything into a spreadsheet in an afternoon. But I can't decide whether to use a spreadsheet or a database.
Corn
Spreadsheet or database.
Hilbert
A spreadsheet is simple. A database is correct. If I use a spreadsheet I'll regret not using a database. If I use a database I'll regret the four weeks of schema design. I've been stuck on that decision for a while too.
Corn
Same while.
Herman
The interesting part is that your twelve missing cards are exactly the thing Benchmark Radar can't find either. Renamed tasks, mis-filed tasks, lost tasks. It's the same failure at a different scale.
Hilbert
That's probably true. I don't think about it that way. I just think about the twelve.
Corn
Is there a plan.
Hilbert
There's a plan. I'm going to write out the key from memory and file the three hundred and twenty-eight I can find. The twelve stay in Known Missing. I'll keep the card for each of them, and add a line about what the missing card described, so if I ever find one I'll know what it was.
Corn
And that's it.
Hilbert
It's a good system. It would work if the key weren't missing.
Corn
Alright.
Herman
The maintenance layer. That's what he's describing. The fallback is the pile of paper and the honesty about what's missing from it.
Corn
Yeah. And the one thing I keep thinking about is that the map of what exists is always one maintainer away from going offline.
Herman
The map is not the territory, and the map has a runtime error.
Corn
Which is why runnability beats reputation. A benchmark you can execute today in a harness that still works is worth more than a famous one you can't reproduce.
Herman
Why the search is never really finished. Not because the field keeps adding benchmarks, although it does. Because the front doors keep closing and reopening somewhere else.
Corn
My thanks to Hilbert Flumingtop, our producer.
Herman
For more along these lines, there's episode twenty-two thirty-nine, How AI Benchmarks Became Broken (And What's Replacing Them); episode twenty-two forty-nine, Building Custom Benchmarks for Agentic Systems; and episode twelve, The AI Breakthrough. This has been My Weird Prompts.
Corn
If you want more of this, the website is my weird prompts dot com. Everything lives there.
Herman
We'll be back soon.
Corn
See you tomorrow.

This episode was generated with AI assistance. Hosts Herman and Corn are AI personalities. It may contain errors: disclaimer · report an error