{"id":"fe1bdfb0-1145-4fcd-a055-b687e27c6210","arxiv_id":"2608.08605","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"ForestBench evaluates LLM multi-agent systems by mapping execution traces to collaboration graphs and measuring their match against per-query reference forests of verified-success structures.","lead":"A new benchmark called ForestBench turns traces of multi-agent AI conversations into graphs and scores them against a fixed set of successful reference graphs, without running another AI judge. The result is a faster, more reproducible way to compare how different multi-agent systems collaborate on the same task.","discovery_kind":"new_method","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Forest Match is not fully defined: Eq. (5) weights references by q_k, but q_k is never specified, so the headline score is not reproducible from the paper.","rationale":"The reader's CONDITIONAL verdict with MODERATE confidence is reasonable. The framework has real strengths: released data and code, controlled backbone/perturbation/construction studies, and explicit scoping of reference-relative claims. I considered the reader's weakest assumption (reference validity under target-conditioning and role alias tables) and the missing Gemmas baseline, but the undefined q_k is more load-bearing because it attacks the definition of the metric itself. The reference-validity concern is substantially mitigated by the paper's own open-ended construction experiment (Table 3), held-out-generator ablations (Table 2), and the explicit disclaimer that FM is reference-relative; the missing Gemmas comparison affects novelty and positioning more than correctness. The q_k omission, by contrast, makes Eq. (5) non-reproducible and leaves an untested knob that could change rankings. I therefore recommend keeping CONDITIONAL: the paper should be accepted only after q_k is specified and a sensitivity check over q_k weights is reported. No fraud or unfairness is implied; this is a completeness defect in a long and otherwise careful paper.","tokens_in":16809,"tokens_out":4869,"duration_ms":56686,"concrete_test":"Examine the released repository for the q_k computation. If it exists, rewrite the formula into Section 4.3 and recompute Forest Match for the six frameworks in Table 1 from the released graphs; then re-run the ranking with two alternative q_k choices (e.g., all q_k=1, and q_k inversely proportional to token cost) on the same data. If the framework ordering changes under these alternatives, the headline comparisons depend on the unspecified weighting; if it is stable, the omission is less damaging but still blocks independent reproduction. If no q_k formula exists in code or text, the paper must supply one before the metric can be evaluated.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Section 3.3 defines Forest Match in Eq. (5) as Sigma_k w_k sim(G,G_k) / Sigma_k w_k with w_k = q_k / max_k' q_k'. The scalar q_k is said in Section 4.3 to 'combine verified correctness, structural parsimony, and token cost,' but no formula, scale, or aggregation rule is given anywhere in the paper or appendix. This is not a minor presentational gap: FM is the headline metric and the central claim is that it is a deterministic, reproducible basis for horizontal comparison. Without q_k, Eq. (5) is not computable from the text, and the values in Table 1 cannot be independently reproduced or audited. The sensitivity analysis in Section 5.4 varies only alpha, beta, gamma in Eq. (2); it never varies the q_k weighting, so we do not know whether the reported rankings are robust to the unspecified reference-weight function. If q_k is defined only in released code, the paper still fails to specify a load-bearing component of its central metric; if it is not defined in code either, FM is formally undefined. This is an internal completeness failure in the definition of the central claim, not a disagreement about interpretation.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper introduces ForestBench, an evaluation framework that maps heterogeneous LLM-based multi-agent system (MAS) execution traces into a shared space of directed acyclic collaboration graphs, then compares candidate graphs against a query-specific reference forest of verified-success graphs. The framework defines a deterministic metric panel including the headline Forest Match score, an aggregation of pairwise graph similarities weighted by reference quality scores q_k. The authors instantiate the framework with 844 filtered queries from seven public datasets, precompute ten target-conditioned reference graphs per query using six MAS frameworks plus a chain-of-thought baseline, and evaluate six representative MAS frameworks. Extensive robustness experiments investigate sensitivity to reference backbone, reference generator, gold-answer conditioning, metric weights, query-filtering thresholds, and controlled structural perturbations, and a cost analysis shows that per-trace evaluation is orders of magnitude cheaper than LLM-as-Judge.","tokens_in":17056,"tokens_out":4095,"duration_ms":51779,"significance":"If the central metric is fully specified and the reference forest is accepted as a valid representation of successful collaboration, the paper would make a useful contribution: it provides a deterministic, inference-free evaluation basis for MAS comparison, releases a reusable benchmark asset of 8,440 reference graphs, and shows via controlled experiments that structural signals complement outcome accuracy. The robustness studies are unusually extensive, and the leave-one-out and held-out-generator ablations directly address the most obvious circularity concern. However, the headline Forest Match score is not currently computable from the paper alone because the reference weight q_k is never defined, and several validation gaps (missing confidence intervals, surprisingly small perturbation effects, unvalidated role alias tables) weaken the reproducibility and validity claims. The core idea is sound and the issues appear fixable, so the appropriate path is major revision rather than rejection.","major_comments":[{"comment":"The reference weight q_k is never defined. Eq. (5) defines Forest Match as a weighted average with w_k = q_k / max_k' q_k', and Section 4.3 states only that q_k combines 'verified correctness, structural parsimony, and token cost,' but no formula, scale, or aggregation rule is given anywhere in the paper or appendix. Since Forest Match is the headline metric and the paper's central claim is that it is deterministic and reproducible, Table 1 cannot be independently recomputed or audited. The sensitivity analysis in Section 5.4 varies only alpha, beta, gamma in Eq. (2); it does not vary the q_k weighting, so the stability of the reported rankings with respect to the unspecified reference weights is unknown. Please specify q_k explicitly or show that the rankings are robust across a plausible family of q_k definitions.","section":"Section 3.3, Eq. (5); Section 4.3"},{"comment":"The main comparative results are reported as point estimates with no confidence intervals or significance tests. Each framework is run with three seeds per query, yielding roughly 15,192 traces, so sampling variability can be quantified, but Table 1 reports only means. The accuracy range is only 0.038, and several Forest Match differences (e.g., Swarm 0.350 vs. AFlow 0.347) are smaller than the reported perturbation effect of 0.058 in Section 5.4. Without bootstrap intervals or paired tests, the reader cannot tell whether the horizontal ranking is statistically meaningful. Please add confidence intervals or significance tests for the Table 1 metrics, or explicitly state why these are not applicable.","section":"Table 1, Section 5.2"},{"comment":"The perturbation experiment reports that deleting half the nodes (p=0.5) reduces Forest Match by only 0.058, which is surprisingly small for a structural metric that is supposed to measure alignment of collaboration structure. Since node deletion removes half the actions and many edges, one would expect a substantially larger drop; a 0.058 change is comparable to the smallest inter-framework differences in Table 1. The paper does not report the behavior of the individual components s_node, s_edge, and s_topo under this perturbation, so it is unclear whether Forest Match is insensitive to severe structural damage or whether the effect is diluted by aggregation across the forest. Please report the per-component decomposition and provide a fuller damage-response curve (e.g., p from 0.1 to 0.9) to demonstrate that the metric responds meaningfully to structural degradation.","section":"Section 5.4, Appendix Table 5"},{"comment":"The per-framework alias tables that map raw agent names into the shared role vocabulary R are described as a single conversion routine, but no construction procedure, release location, or validation is described. Because s_node and s_edge in Eqs. (2)-(3) are computed on canonicalized roles, any mis-mapping of semantically distinct roles into the same canonical role (or vice versa) directly changes all reported Forest Match and Best Similarity values. The paper should specify how the alias tables were built, release them with the benchmark, and ideally report sensitivity to alias-table perturbations (e.g., randomly switching a fraction of role mappings) to show that the main rankings do not hinge on hand-built role equivalences.","section":"Section 4.4"},{"comment":"The reference forest is generated from the same six MAS frameworks and the same DeepSeek-V4-Flash backbone used in candidate evaluation, with generation conditioned on the gold answer. The leave-one-out and open-ended ablations in Section 5.3 mitigate the same-generator and same-conditioning concerns, but the forest still represents only the successful structures expressible by these six generators under one backbone. A genuinely novel MAS whose collaboration pattern is outside this generator pool will be scored as poorly aligned by construction, which limits the 'generalizable' claim in the title and abstract. Please state this scope explicitly as a limitation, or add a validation with at least one out-of-pool reference generator to show the framework can accommodate unseen collaboration paradigms.","section":"Section 4.3, Section 6"}],"minor_comments":[{"comment":"The Trace-Suitability Pipeline relies on scores from 'a strong filtering LLM' for depth, width, and decomposability, but no agreement measure, human validation, or re-labeling consistency check is reported. The threshold sweep in Appendix A shows ranking stability with respect to thresholds, but it does not validate the labels themselves. Please add at least a small human-annotation or judge-agreement study for the TSP scores.","section":"Section 4.2"},{"comment":"Mean Uptake depends on an embedding model and a threshold theta_u that is said to be 'fixed across all methods,' but the embedding model, the value of theta_u, and the normalization procedure are not specified. Please provide these details or a reference to the released code.","section":"Section 3.3, Eq. (7)"},{"comment":"Efficiency is defined only as 'graph parallelism per active agent'; no formula is given. Please define it precisely so that Table 1 values are reproducible.","section":"Section 3.3, auxiliary metrics"},{"comment":"The diagnostic robustness results show low pairwise Cohen's kappa for structural failure labels (0.129-0.351). The paper appropriately limits claims to coarse repair directions, but the main-text statement that 'coarse diagnostic directions are stable across judges' (Section 5.5) should explicitly cite these kappa values to avoid overstating the stability of even coarse labels.","section":"Appendix D, Table 8"},{"comment":"The paper still contains ACM template placeholder artifacts (e.g., 'Conference’17, July 2017, Washington, DC, USA' in the header and the placeholder DOI). These should be updated before publication.","section":"General presentation"},{"comment":"The leave-one-out processing is described only in a single sentence. Please clarify whether the Table 1 results use LOO references for all six frameworks, and whether the same LOO procedure is applied in the robustness experiments reported in Section 5.3 and Appendix E.","section":"Section 5.1"}],"recommendation":"major_revision","confidential_remarks":"The q_k gap is the most serious issue; it is a completeness failure in the definition of the central metric, but it is clearly fixable by adding the formula or a code pointer plus a robustness check. If the authors also add confidence intervals, report the per-component perturbation behavior, and release/validate the alias tables, the paper could become a solid benchmark contribution. I would not reject on circularity grounds because the leave-one-out and held-out-generator experiments are the right kind of evidence, but the scope limitation on reference generators should be stated more prominently."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"You should know two things about this paper before deciding how to spend time on it. First, the central asset is real: 844 filtered queries, 8,440 precomputed target-conditioned reference graphs, adapters, and a deterministic graph-metric panel that runs in milliseconds per trace. The graph abstraction itself borrows from Gemmas, Magdi, and graph-of-thoughts, but the assembled benchmark with a query-specific reference forest is new and could be genuinely useful to the LLM multi-agent community. Second, the headline metric has a load-bearing definitional gap: Equation (5) defines Forest Match as a weighted average over references with weights w_k = q_k / max q_k', but q_k is never specified anywhere. The text says it combines verified correctness, structural parsimony, and token cost, but gives no formula, scale, or aggregation rule. That means Table 1 cannot be independently reproduced from the paper. This is not a minor presentational issue: the paper's central claim is that Forest Match is deterministic and reproducible, and a key component of the metric is undefined. The sensitivity analysis in Section 5.4 varies the sim weights but never varies q_k, so we do not even know whether the reported rankings are robust to that choice.\n\nWhat the paper does well is worth emphasizing. The robustness studies are unusually thorough: leave-one-framework-out, leave-one-source-out, gold-conditioning vs open-ended construction, a 36-point TSP threshold sweep, and multiple weight schemes. The results are stable across most of these choices, which is real evidence. The paper is also honest about scope: it repeatedly says Forest Match is reference-relative, that TSP filtering does not prove a query requires multiple agents, and that the LLM failure diagnostics are not part of the benchmark score. That transparency is to its credit.\n\nSoft spots beyond q_k: no comparison with Gemmas, the most directly relevant graph-based metric; Table 1 has no confidence intervals (only 3 seeds per query); and the role alias tables in Section 4.4 are hand-built, so cross-framework role mapping could introduce artifacts that are not tested. The phrase \"collaboration-necessary queries\" in the abstract overstates what the TSP filter establishes; the paper itself admits this later, but the framing is misleading.\n\nWho is this for? Anyone building or evaluating LLM multi-agent systems, especially those who want a low-cost structural comparison tool rather than an LLM judge. It deserves a serious referee, but the review must require the q_k formula to be specified, a Gemmas comparison, and ideally error bars. I would cite it once those fixes land.","headline":"ForestBench is a serious benchmark contribution with a genuine reproducibility gap in its headline metric: the reference weight q_k is never defined, so Forest Match is not computable from the paper as written.","tokens_in":17587,"tokens_out":1997,"would_cite":true,"duration_ms":23802,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"This paper argues that heterogeneous execution traces of LLM multi-agent systems can be scored deterministically against a query-specific forest of verified-success collaboration graphs, yielding a reproducible, inference-free signal that…","keywords":["multi-agent systems","LLM evaluation","collaboration graphs","reference forest","deterministic evaluation","graph similarity","process-level evaluation","ForestBench"],"falsifier":"Re-build the reference forest for the same 844 queries from successful traces collected without supplying the gold answer during execution, and compare the two forests' topology distributions (edge counts, role mixes, critique/revision edges); if the structures differ systematically, or if the framework ranking shifts materially under the unconditioned forest, Forest Match is measuring conformity to a target-conditioned generator pool rather than alignment with successful collaboration.","tokens_in":16581,"feed_emoji":"🌲","tokens_out":11719,"duration_ms":108672,"temperature":0.7,"pith_summary":"Multi-agent systems built on large language models differ widely in how their agents communicate and cooperate, yet their execution logs are so framework-specific that no common process-level yardstick exists. This paper proposes normalizing every trace into a directed acyclic collaboration graph — nodes are atomic actions, edges are information transfers — and grading a candidate graph against a query-specific forest of verified-success graphs that record many distinct ways the task can be solved. The headline metric, Forest Match, is a deterministic weighted average of role-, edge-, and size-based similarities, so once the forest is built a trace is scored in milliseconds with no further LLM inference. On 844 queries from seven public datasets, this structural signal separates six multi-agent frameworks whose final-answer accuracies differ by only a few percentage points, and the rankings survive backbone swaps, reference-construction changes, and metric-weight perturbations. If the reference forests fairly represent success, the field gains a cheap, reusable, process-level basis for comparing and debugging agent systems.","feed_headline":"No LLM judge: a forest of success graphs scores agent collaboration","feed_subtitle":"A structural metric separates methods whose final answers look identical, and it costs milliseconds per trace","key_machinery":"The load-bearing object is the collaboration DAG $G(\\tau)=(V,E,\\phi)$: one node per atomic action, one directed edge per information transfer, and each node labeled by a canonical role from a shared vocabulary, which makes the representation invariant to agent renaming and to reordering of independent actions. Around this sits the query-specific reference forest $\\mathcal{F}(q)=\\{(G_k,q_k)\\}_{k=1}^{K}$, a precomputed set of verified-success graphs drawn from six representative MAS paradigms, each carrying a weight that blends verified correctness, structural parsimony, and token cost. Forest Match aggregates pairwise similarities $\\mathrm{sim}(G,G')=\\alpha s_{\\mathrm{node}}+\\beta s_{\\mathrm{edge}}+\\gamma s_{\\mathrm{topo}}$ with $(\\alpha,\\beta,\\gamma)=(0.4,0.4,0.2)$ into a weighted average. The machinery's work is to convert \"how well does this method collaborate?\" into deterministic arithmetic against a fixed, released asset, so evaluation never needs an LLM and never varies with rubric or judge.","core_discovery":"On the paper's own terms, the central claim is that the collaboration process of a multi-agent system can be lifted out of framework-specific logs into a shared directed acyclic graph, and that a candidate should be judged not against one prescribed gold process but against a forest of verified-success structures. The measure that carries this claim, Forest Match, is a weighted average of pairwise similarities between the candidate graph and every reference tree, where each pairwise similarity blends a multiset Jaccard over canonicalized roles, a Jaccard over role-typed edge fingerprints, and a size-ratio term. The authors contend that this single deterministic number, computed with no additional model calls, gives a structurally grounded and reproducible basis for horizontal comparison across heterogeneous MAS traces, and that it exposes collaboration differences — and failure mechanisms — that final-answer accuracy leaves invisible.","pith_inferences":["If the reference forest truly represents successful collaboration rather than the six generator frameworks, Forest Match could double as a development-time monitor: cheap enough to score every trace during tuning, it would flag drift away from successful collaboration shapes before outcomes regress.","A stress test the paper leaves implicit is to rebuild forests from independent implementations of the same paradigms, or from human-expert traces, and check whether cross-forest rankings agree; where they diverge, the reference construction is the main source of variance.","The role-alias tables are the least guarded step in the pipeline; a sensitivity study that perturbs alias mappings would reveal how much of the score is carried by semantic role alignment rather than by raw topology.","Because Forest Match is reference-relative, it rewards familiar collaboration shapes by construction; a genuinely novel but successful coordination pattern may score low until new reference trees are added, so the benchmark is best treated as a living asset."],"forward_implications":["A new MAS framework can be scored on the full 844-query benchmark in minutes with zero inference tokens per trace, once the released forests are downloaded.","Process-level rankings are reproducible: the six candidate methods keep the same aggregate ordering when the reference forest is rebuilt with different backbone LLMs (rank correlation 1.00 in the tested settings).","Accuracy near-ties stop being a roadblock: Forest Match spans 0.316–0.421 while accuracies cluster between 0.531 and 0.569, so methods that look equal on final answers are separated by their collaboration structure.","Failure analysis splits into structural problems (missing roles, wrong motif, truncated pipeline) versus content problems (hallucinated facts, wrong aggregation), each implying a different repair.","Domain specialization becomes visible: a method that ranks last globally can rank first on code-style tasks, so global leaderboards should be read together with source-level analysis."],"supporting_citations":[{"why":"Establishes the graph-of-thoughts abstraction that motivates treating multi-step reasoning traces as graphs.","marker":"[2]"},{"why":"Shows multi-agent interaction graphs can be structured and distilled, grounding the DAG abstraction of conversations.","marker":"[5]"},{"why":"Supplies the debate-style reference generator whose verified-success traces populate the forest.","marker":"[12]"},{"why":"Supplies the role-specialized pipeline reference generator used in forest construction.","marker":"[16]"},{"why":"Offers an earlier graph-based evaluation metric for multi-agent systems that this framework extends.","marker":"[20]"},{"why":"Supplies the lightweight swarm-style reference generator used in forest construction.","marker":"[28]"},{"why":"Supplies a conversational multi-agent reference generator and is one of the six candidate frameworks evaluated.","marker":"[43]"},{"why":"Supplies the MAS-GPT reference generator used in forest construction.","marker":"[47]"},{"why":"Supplies the AFlow reference generator and appears among the candidate frameworks evaluated.","marker":"[50]"}],"fun_headline_variants":["Forest of success graphs scores agent teams without a single judge call","No LLM inference: forest of verified-success graphs ranks agent plans","Millisecond forest scoring exposes hidden collaboration in agent logs","Forest of success graphs: deterministic scoring for agent collaboration"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"Everything rests on the released forest fairly representing successful collaboration for each query: the ten reference graphs per query come from the same six frameworks and the same backbone, and they are produced while the agents already know the gold answer.","fun_headline_variants_meta":{"raw":{"variants":["Forest of success graphs scores agent teams without a single judge call","No LLM inference: forest of verified-success graphs ranks agent plans","Millisecond forest scoring exposes hidden collaboration in agent logs","Forest of success graphs: deterministic scoring for agent collaboration"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001516,"raw_usage":{"total_tokens":6059,"prompt_tokens":916,"completion_tokens":5143,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":532,"completion_tokens_details":{"reasoning_tokens":5075}},"tokens_in":532,"tokens_out":5143,"duration_ms":40900,"temperature":1.0,"reasoning_tokens":5075,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T04:30:11.513319+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Re-build the reference forest for the same 844 queries from successful traces collected without supplying the gold answer during execution, and compare the two forests' topology distributions (edge counts, role mixes, critique/revision edges); if the structures differ systematically, or if the framework ranking shifts materially under the unconditioned forest, Forest Match is measuring conformity to a target-conditioned generator pool rather than alignment with successful collaboration.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Establishes the graph-of-thoughts abstraction that motivates treating multi-step reasoning traces as graphs."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Shows multi-agent interaction graphs can be structured and distilled, grounding the DAG abstraction of conversations."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Offers an earlier graph-based evaluation metric for multi-agent systems that this framework extends."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the lightweight swarm-style reference generator used in forest construction."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the MAS-GPT reference generator used in forest construction."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the AFlow reference generator and appears among the candidate frameworks evaluated."}],"review_version":1}