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Environment-free Synthetic Data Generation for API-Calling Agents

Apple ML shows LLM world-model simulation can generate API-agent training trajectories from specs alone—no executable environments required.

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Environment-free Synthetic Data Generation for API-Calling Agents

What the paper does

Apple ML Research generates synthetic trajectories for API-calling agents using LLMs as on-the-fly digital world models. Given only API specifications, an LLM creates tasks; a teacher agent solves them while an LLM simulator emits coherent stateful API responses; an LLM judge filters quality.

Key findings

  • Collecting real trajectories usually needs full environments and populated backends—a scalability bottleneck.
  • Environment-free simulation from specs alone produced useful supervision on AppWorld and OfficeBench (IR and state-changing tasks).
  • Fine-tuning on the synthetic data yielded significant gains, establishing LLM-based API simulation as a practical training path.

Why it matters

Decouples agent post-training data from environment engineering cost—important for MCP/tool ecosystems that change faster than sandboxes can be built.

Related

Source: https://machinelearning.apple.com/research/environment-free | 2026-07-23

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