How are AI agents used? Evidence from 177,000 MCP tools
On the map: LLM agents and tool use → Tool learning and function calling
Abstract (arXiv)
Today's AI agents are built on large language models (LLMs) equipped with tools to access and modify external environments, such as corporate file systems, API-accessible platforms and websites. AI agents offer the promise of automating computer-based tasks across the economy. However, developers, researchers and governments lack an understanding of how AI agents are currently being used, and for what kinds of (consequential) tasks. To address this gap, we evaluated 177,436 agent tools created from 11/2024 to 02/2026 by monitoring public Model Context Protocol (MCP) server repositories, the current predominant standard for agent tools. We categorise tools according to their direct impact: perception tools to access and read data, reasoning tools to analyse data or concepts, and action tools to directly modify external environments, like file editing, sending emails or steering drones in the physical world. We use O*NET mapping to identify each tool's task domain and consequentiality. Software development accounts for 67% of all agent tools, and 90% of MCP server downloads. Notably, the share of 'action' tools rose from 27% to 65% of total usage over the 16-month period sampled. While most action tools support medium-stakes tasks like editing files, there are action tools for higher-stakes tasks like financial transactions. Using agentic financial transactions as an example, we demonstrate how governments and regulators can use this monitoring method to extend oversight beyond model outputs to the tool layer to monitor risks of agent deployment.
Key facts. Cited by 7 papers in the map (data through 7 Oct 2026). Placed in Tool learning and function calling, one of 16 directions in LLM agents and tool use. Builds on 25 of its 70 references that are in the map. First posted on arXiv 25 Mar 2026.
Builds on
25 of 70 references.
References · 25
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13 more
- 2025Future of Work with AI Agents: Auditing Automation and Augmentation Potential across the U.S. Workforcecited by 33
- 2025Characterizing AI Agents for Alignment and Governancecited by 30
- 2025EchoLeak: The First Real-World Zero-Click Prompt Injection Exploit in a Production LLM Systemcited by 26
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Built on by
Citing papers per year: 2026: 7.
7 papers.
- 2026HarmfulSkillBench: How Do Harmful Skills Weaponize Your Agents?cited by 9
- 2026A Formal Security Framework for MCP-Based AI Agents: Threat Taxonomy, Verification Models, and Defense Mechanismscited by 2
- 2026Measuring Harness-Induced Belief Divergence in Multi-Step LLM Agentscited by 1
- 2026AGNT2: Autonomous Agent Economies on Interaction-Optimized Layer 2 Infrastructurecited by 0
- 2026An Empirical Study of Model Context Protocol Applicationscited by 0
- 2026When Agents Act on Web3: An Attack-Surface Survey of MCP, Skills, and Tool Callingcited by 0
- 2026A Two-Dimensional Study of the Model Context Protocol: Publication and Adoptioncited by 0
- 2026A Two-Dimensional Study of the Model Context Protocol: Publication and Adoption13 Sep 2026
- 2026When Agents Act on Web3: An Attack-Surface Survey of MCP, Skills, and Tool Calling18 Aug 2026
- 2026An Empirical Study of Model Context Protocol Applications28 Jul 2026
- 2026Measuring Harness-Induced Belief Divergence in Multi-Step LLM Agents5 Jul 2026
- 2026AGNT2: Autonomous Agent Economies on Interaction-Optimized Layer 2 Infrastructure22 Apr 2026
- 2026HarmfulSkillBench: How Do Harmful Skills Weaponize Your Agents?16 Apr 2026
- 2026A Formal Security Framework for MCP-Based AI Agents: Threat Taxonomy, Verification Models, and Defense Mechanisms7 Apr 2026
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