Meta trains an 8B model to pick tools better than a 402B Llama-4-Maverick

dair_ai · x · 2026-10-23

A Meta/CMU paper tackles tool selection for agents facing corpora of 10,000+ tools, where descriptions overflow the context and retrievers can only rank candidates without knowing which tools an instruction actually needs.

Their recipe trains Qwen3 models on a Plan-Retrieve-Select workflow: the model decomposes instructions into substeps, a retriever fetches candidates per substep, and the model commits one tool each. Training is SFT on 20K curated ToolBench instructions followed by RL with a reward scoring gold-tool coverage and rank.

On ToolBench G3, Qwen3-8B improves from 36.2% after SFT to 41.5% after RL, beating prompted Llama-4-Maverick (402B), and the trained model transfers across retrievers and novel tool corpora.

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