Researchers at Google and MIT have conducted a comprehensive analysis of agentic systems and the dynamics between the number of agents, coordination structure, model capability, and task properties. While the prevailing sentiment in the industry has been "more agents is all you need," the research suggests that scaling agent teams is not a guaranteed path to better performance. Based on their findings, the researchers have defined a quantitative model that can predict the performance of an agentic system on an unseen task. Their work reveals that adding more agents and tools acts as a double-edged sword: Although it can unlock performance on specific problems, it often introduces unnecessary overhead and diminishing returns on others. These findings offer a critical roadmap for developers and enterprise decision-makers trying to determine when to deploy complex multi-agent architectures versus simpler, more cost-effective single-agent solutions. The state of agentic systems To understand the study's implications, it is necessary to distinguish between the two primary architectures in use today. Single-agent systems (SAS) feature a solitary reasoning locus. In this setup, all perception, planning, and action occur within a single sequential loop controlled by one LLM instance, even when the system is using tools, self-reflection, or chain-of-thought (CoT) reasoning. Conversely, a multi-agent system (MAS) comprises multiple LLM-backed agents communicating through structured message passing, shared memory, or orchestrated protocols. The enterprise sector has seen a surge in interest regarding MAS, driven by the premise that specialized collaboration can consistently outperform single-agent systems. As tasks grow in complexity and require sustained interaction with environments (e.g., coding assistants or financial analysis bots) developers often assume that splitting the work among "specialist" agents is the superior approach. However, the researchers argue that despite this rapid adoption, there remains no principled quantitative framework to predict when adding agents amplifies performance and when it erodes it. A key contribution of the paper is the distinction between "static" and "agentic" tasks. The researchers applied an "Agentic Benchmark Checklist" to differentiate tasks that require sustained multi-step interactions, iterative information gathering, and adaptive strategy refinement from those that do not. This distinction is vital because strategies that work for static problem-solving (like voting on a coding quiz) often fail when applied to true agentic tasks where "coordination overhead” and “error propagation” can spread across the problem-solving process. Testing the limits of collaboration To isolate the specific effects of system architecture, the researchers designed a rigorous experimental framework. They tested 180 unique configurations involving five distinct architectures, three LLM families (OpenAI, Google, and Anthropic), and four agentic benchmarks. The architectures included a single-agent control group and four multi-agent variants: independent (parallel agents with no communication), centralized (agents reporting to an orchestrator), decentralized (peer-to-peer debate), and hybrid (a mix of hierarchy and peer communication). The study was designed to eliminate "implementation confounds" by standardizing tools, prompt structures, and token budgets. This ensured that if a multi-agent system outperformed a single agent, the gain could be attributed to the coordination structure rather than access to better tools or more compute. The results challenge the "more is better" narrative. The evaluation reveals that the effectiveness of multi-agent systems is governed by "quantifiable trade-offs between architectural properties and task characteristics." The researchers identified three dominant patterns driving these results: Tool-coordination trade-off: Under fixed computational budgets, multi-agent systems suffer from context fragmentation. When a compute budget is split among multiple agents, each agent is left with insufficient capacity for tool orchestration compared to a single agent that maintains a unified memory stream. Consequently, in tool-heavy environments with more than 10 tools, the efficiency of multi-agent systems drops sharply. The researcher found that tool-heavy tasks suffer a 2–6× efficiency penalty when using multi-agent systems compared to single agents. Simpler architectures paradoxically become more effective because they avoid the coordination overhead that compounds with environmental complexity. Capability saturation: The data established an empirical threshold of approximately 45% accuracy for single-agent performance. Once a single-agent baseline exceeds this level, adding more agents typically yields diminishing or negative returns. However, co-author Xin Liu, a research scientist at Google and co-author of the paper, noted a crucial nuance for enterprise adopters. "Enterprises should invest in both [single- and multi-agent systems],” he told VentureBeat. “Better base models raise the baseline, but for tasks with natural decomposability and parallelization potential (like our Finance Agent benchmark with +80.9% improvement), multi-agent coordination continues to provide substantial value regardless of model capability." Topology-dependent error: The structure of the agent team determines whether errors are corrected or multiplied. In "independent" systems where agents work in parallel without communicating, errors were amplified by 17.2 times compared to the single-agent baseline. In contrast, centralized architectures contained this amplification to 4.4 times. "The key differentiator is having a dedicated validation bottleneck that intercepts errors before they propagate to the final output," said lead author Yubin Kim, a doctorate student at MIT. "For logical contradictions, 'centralized' reduces the baseline rate … [by] 36.4% … For context omission errors, 'centralized' reduces … [by] 66.8%." Actionable insights for enterprise deployment For developers and enterprise leaders, these findings offer specific guidelines for building more efficient AI systems. The "sequentiality" rule: Before building a team of agents, analyze the dependency structure of your task. The strongest predictor of multi-agent failure is strictly sequential tasks. If Step B relies entirely on the perfect execution of Step A, a single-agent system is likely the better choice. In these scenarios, errors cascade rather than cancel out. Conversely, if the task is parallel or decomposable (e.g., analyzing three different financial reports simultaneously) multi-agent systems offer massive gains. Don't fix what isn't broken: Enterprises should always benchmark with a single agent first. If a single-agent system achieves a success rate higher than 45% on a specific task that cannot be easily decomposed, adding more agents will likely degrade performance and increase costs without delivering value. Count your APIs: Be extremely cautious when applying multi-agent systems to tasks that require many distinct tools. Splitting a token budget among multiple agents fragments their memory and context. "For tool-heavy integrations with more than approximately 10 tools, single-agent systems are likely preferable," Kim said, noting that the study observed a "2 to 6x efficiency penalty" for multi-agent variants in these scenarios. Match topology to goal: If a multi-agent system is necessary, the topology must match the specific goal. For tasks requiring high accuracy and precision, such as finance or coding, centralized coordination is superior because the orchestrator provides a necessary verification layer. For tasks requiring exploration, such as dynamic web browsing, decentralized coordination excels by allowing agents to explore different paths simultaneously. The "Rule of 4": While it might be tempting to build massive swarms, the study found that effective team sizes are currently limited to around three or four agents. "The three-to-four- agent limit we identify stems from measurable resource constraints," Kim said. Beyond this, the communication overhead grows super-linearly (specifically, with an exponent of 1.724), meaning the cost of coordination rapidly outpaces the value of the added reasoning. Looking forward: Breaking the bandwidth limit While current architectures hit a ceiling at small team sizes, this is likely a constraint of current protocols rather than a fundamental limit of AI. The effective limit of multi-agent systems stems from the fact that agents currently communicate in a dense, resource-intensive manner. “We believe this is a current constraint, not a permanent ceiling,” Kim said, pointing to a few key innovations that can unlock the potential of massive-scale agent collaboration:  Sparse communication protocols: “Our data shows message density saturates at approximately 0.39 messages per turn, beyond which additional messages add redundancy rather than novel information. Smarter routing could reduce overhead,” he said. Hierarchical decomposition: Rather than flat 100-agent swarms, nested coordination structures could partition the communication graph. Asynchronous coordination: “Our experiments used synchronous protocols, and asynchronous designs might reduce blocking overhead,” he said.  Capability-aware routing: “Our heterogeneity experiments suggest that mixing model capabilities strategically can improve efficiency,” Kim said This is something to look forward to in 2026. Until then, for the enterprise architect, the data is clear: smaller, smarter, and more structured teams win.