hkust-nlp/Toolathlon

[ICLR 2026] The Tool Decathlon: Benchmarking Language Agents for Diverse, Realistic, and Long-Horizon Task Execution

What it solves

Toolathlon is a benchmark designed to evaluate how well language agents can use a wide variety of tools to complete complex, long-horizon tasks in realistic software environments. It addresses the need for a standardized way to test an agent's ability to execute multi-step workflows across diverse real-world applications.

How it works

The project provides a comprehensive testing suite featuring over 600 diverse tools. It uses containerization (via Docker or Podman) to create isolated environments for each task, ensuring that agent executions do not interfere with one another. Users can run evaluations through a public service, a local setup, or a decoupled mode where the agent loop runs on the host while the environment remains in a container. It also includes a visualization tool to replay and analyze the reasoning trajectories of the LLMs.

Who it’s for

This tool is primarily for AI researchers and developers building language agents who need to rigorously benchmark their models' tool-use capabilities and long-term planning in realistic scenarios.

Highlights

  • Extensive Toolset: Includes over 600 tools based on real-world software.
  • Long-Horizon Tasks: Focuses on tasks that require multiple sequential tool calls to complete.
  • Isolated Execution: Uses containerized environments to ensure task isolation and parallel evaluation.
  • Flexible Integration: Supports multiple agent scaffolds, including a default implementation and the Claude Agent SDK, with preliminary integration for OpenHands.
  • Trajectory Visualization: Provides a built-in server to replay and visualize LLM reasoning paths.

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