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Evaluation and Coordination Benchmarks ​

Five 2025-2026 benchmarks cover the multi-agent evaluation space. MultiAgentBench / MARBLE (ACL 2025, arXiv:2503.01935) evaluates star/chain/tree/graph topologies with milestone KPIs; graph is best for research, cognitive planning adds ~3% milestone achievement. COMMA evaluates multimodal asymmetric-information coordination; state-of-the-art models including GPT-4o struggle to beat a random baseline. MedAgentBoard (arXiv:2505.12371) covers four medical task categories and often finds multi-agent does not dominate single-LLM. AgentArch (arXiv:2509.10769) benchmarks enterprise agent architectures combining tool-use + memory + orchestration. SWE-bench Pro (arXiv:2509.16941) has 1865 problems across 41 repos spanning business apps, B2B services, and developer tools; frontier models score ~23% on Pro vs 70%+ on Verified — a reality check on contamination. Claude Opus 4.7 (April 2026) is reported at 64.3% on Pro with explicit agent-teams coordination (no Anthropic primary source published yet — treat as preliminary); Verdent (agent scaffold) hits 76.1% pass@1 on Verified (Verdent technical report). AAAI 2026 Bridge Program WMAC (https://multiagents.org/2026/) is the 2026 community focal point. This lesson builds on MARBLE's metrics, runs a topology-vs-metric sweep, and pins the "just passing SWE-bench Verified is not evidence of generalization" rule.

Type: Learn Languages: Python (stdlib) Prerequisites: Phase 16 · 15 (Voting and Debate Topology), Phase 16 · 23 (Failure Modes) Time: ~75 minutes

Problem ​

When a paper claims "our multi-agent system is better," the question is: better than what, on what, measured how? The 2023-2024 era of multi-agent evaluation was chaos — everyone picked their own metrics, their own baselines, and their own task sets. The 2025-2026 benchmarks imposed structure.

Without shared benchmarks, you cannot compare two multi-agent systems meaningfully. Worse, without hold-out benchmarks, frontier models can contaminate. SWE-bench Verified became partially contaminated in training corpora by mid-2025; frontier scores inflated; Pro was designed as an uncontaminated reality check.

This lesson enumerates the five canonical 2026 benchmarks, names what each measures, and teaches you to read benchmark claims skeptically.

Concept ​

MultiAgentBench (MARBLE) — ACL 2025 ​

arXiv:2503.01935. Evaluates four coordination topologies (star, chain, tree, graph) on research, coding, and planning tasks. Milestone-based KPIs track partial progress rather than only final success.

Measured results:

  • Graph topology best for research scenarios; supports any-to-any critique.
  • Chain best for stepwise-refinement coding.
  • Star best for fast-factual consolidation.
  • Coordination tax appears past ~4 agents on graph.
  • Cognitive planning adds ~3% milestone achievement across topologies.

Use when: you want to compare coordination topologies apples-to-apples. The MARBLE repo (https://github.com/ulab-uiuc/MARBLE) provides the evaluator.

COMMA — multimodal asymmetric information ​

Covers tasks where agents have different observation modalities and must coordinate without full information sharing. The reported result is uncomfortable: frontier models including GPT-4o struggle to beat a random baseline on agent-agent collaboration in COMMA. The signal is that multi-agent modalities are under-trained and under-evaluated — LLMs handle single-modality cooperation reasonably; multi-modality coordination collapses.

Use when: your system has multimodal or asymmetric-information coordination. The null result from COMMA is a warning to measure before claiming.

MedAgentBoard — domain stress test ​

arXiv:2505.12371. Four medical task categories: diagnosis, treatment planning, report generation, patient communication. Compares multi-agent vs single-LLM vs conventional rule-based systems.

Finding: multi-agent does NOT dominate single-LLM on most categories. The multi-agent advantage is narrow — task decomposition helps when the subtasks are clearly separable (diagnosis + treatment); it hurts when coordination overhead exceeds specialization gain (report generation).

Use when: your domain has clear-cut single-LLM baselines. If MedAgentBoard's lesson generalizes, many proposed multi-agent systems are over-engineered.

AgentArch — enterprise architectures ​

arXiv:2509.10769. Enterprise settings with tool use, memory, and orchestration layered together. Benchmark isolates the contribution of each layer: how much does adding tools help? Adding memory? Adding multi-agent orchestration?

Use when: you are designing an enterprise agent stack and need to justify each layer. AgentArch helps avoid buying features you cannot measure the value of.

SWE-bench Pro — the reality check ​

arXiv:2509.16941. 1865 problems across 41 repositories spanning business apps, B2B services, and developer tools. Designed to be uncontaminated with later training cutoffs. Frontier models score ~23% on Pro vs 70%+ on Verified. The gap is the contamination signal.

April 2026 scores:

  • Claude Opus 4.7 on Pro: 64.3% (reported with explicit agent-teams coordination; no Anthropic primary source published yet — treat as preliminary).
  • Verdent (agent scaffold) on Verified: 76.1% pass@1 (technical report).
  • Frontier raw scores on Pro without agent scaffolding: ~23-35% (SWE-bench Pro paper).

The takeaway: "we beat SWE-bench Verified" is no longer evidence of capability. Pro is the current gating test. Agent-team scaffolding produces measurable gains on Pro (~30-40 point delta), which is one of the strongest empirical arguments for multi-agent coordination in 2026.

AAAI 2026 WMAC ​

AAAI 2026 Bridge Program — Workshop on Multi-Agent Coordination (https://multiagents.org/2026/). The 2026 community focal point for multi-agent AI research. Accepted papers and workshop proceedings are the canonical venue for evaluating new methods; defer to WMAC-accepted claims over arXiv preprints for production decisions.

Read benchmark claims skeptically — the 2026 checklist ​

When someone claims a multi-agent result:

  1. Which benchmark, which split? SWE-bench Verified vs Pro matters a lot. A number reported on the wrong split is worthless.
  2. Contamination check. Was the benchmark released after the model's training cutoff? If not, treat with caution.
  3. Baseline comparison. Vs single-LLM baseline, vs random, vs prior multi-agent work. Not "vs untuned version of the same system."
  4. Statistical significance. N trials, p-value, confidence interval. Frontier models are high-variance; single runs mislead.
  5. Task diversity. One task or many? Generalization matters for production.
  6. Cost disclosure. Tokens per task, wall-clock. A 90% solution at 20x cost is a business decision, not a capability claim.

What none of the benchmarks measure well ​

  • Long-horizon coordination. Days of wall-clock interaction. All current benchmarks run short.
  • Adversarial resilience. What happens when one agent is malicious or compromised?
  • Drift under deployment. Benchmarks are static; production distributions shift.
  • Cost-normalized performance. Most benchmarks report raw accuracy, not accuracy-per-dollar.

Building your own internal benchmark for the axis you actually care about is often the right move.

Build It ​

code/main.py is a non-interactive walk-through:

  • Simulates 3 multi-agent systems on a toy task.
  • Computes MARBLE-style milestone metrics for each.
  • Runs a contamination check by withholding tasks from a "training" set.
  • Compares to a random baseline explicitly.
  • Prints a benchmark-claims scorecard.

Run:

bash
python3 code/main.py

Expected output: system scorecard with raw accuracy, milestone achievement, cost-per-task, vs-random baseline delta, and a contamination-check note.

Use It ​

outputs/skill-benchmark-reader.md reads any multi-agent benchmark claim and applies the scrutiny checklist. Output: a grade and caveats.

Ship It ​

Production evaluation discipline:

  • Build an internal benchmark that reflects your actual production distribution. Public benchmarks inform but do not substitute.
  • Include a random baseline in every comparison. If you cannot beat random by a large margin on a coordination task, the task may be ill-posed.
  • Report cost alongside accuracy. Token cost and wall-clock. Ops teams need both.
  • Rebuild the benchmark quarterly. Production distribution shifts; stale benchmarks mislead.
  • Avoid published-benchmark overfitting. If your team is optimizing specifically for SWE-bench Pro numbers, you will regress on production.

Exercises ​

  1. Run code/main.py. Identify which of the three simulated systems has the best cost-per-milestone. Does it match the highest raw-accuracy system?
  2. Read MultiAgentBench (arXiv:2503.01935). For your own task domain, decide which of the four topologies MARBLE would recommend. Justify from the paper's results.
  3. Read the SWE-bench Pro paper. What specifically makes it contamination-resistant? Could the same technique be applied to other benchmarks you care about?
  4. Read COMMA's finding on multimodal coordination. Design a simple multimodal coordination task you could add to your internal benchmark. What would count as a useful signal?
  5. Apply the benchmark-claims checklist to one recent multi-agent paper's headline result. What grade would you give the claim?

Key Terms ​

TermWhat people sayWhat it actually means
MARBLE"MultiAgentBench"ACL 2025; star/chain/tree/graph topologies with milestone KPIs.
COMMA"Multimodal benchmark"Multimodal asymmetric-info coordination; frontier models struggle vs random.
MedAgentBoard"Domain stress test"Four medical categories; often finds multi-agent does not dominate single-LLM.
AgentArch"Enterprise benchmark"Tools + memory + orchestration layered.
SWE-bench Pro"Contamination-resistant"1865 problems, 41 repos; ~23% vs 70%+ on Verified (the contamination signal).
Milestone achievement"Partial credit"Benchmarks that reward progress, not only final success.
Contamination"Benchmark leaked into training"Post-release, benchmarks drift into training corpora; scores inflate.
WMAC"AAAI 2026 Bridge Program"Workshop on Multi-Agent Coordination; community focal point.

Further Reading ​