# AWS shows multi-turn RL fine-tuning for search agents on SageMaker AI

Digest AI · Agents & Tools · published 2026-10-02T15:44:20Z

Canonical: https://digestai.news/story/aws-shows-multi-turn-rl-fine-tuning-for-search-agents-on-sagemaker-ai

## Summary

AWS published a tutorial on using Amazon SageMaker AI's multi-turn reinforcement learning (MTRL) to fine-tune a Qwen3.6-27B model into a search agent. The agent uses BM25 and vector search tools across multiple interaction turns to retrieve information. Training used nDCG@10 as a trajectory-level reward, with a -1 penalty for hitting turn or token limits.

The fine-tuned model improved nDCG@10 on three of four benchmarks: +23.7% on BrowseComp-Plus, +18.4% on WixQA, and +6% on Wands, with a slight regression on FreshStack. Failure rates dropped sharply, from 22.89% to 0.68% on BrowseComp-Plus. Training ran with maxepochs=1, globalbatchsize=128, and rolloutmaxconcurrency=32 on serverless infrastructure in the US West (Oregon) region.

## Key points

- Fine-tuned Qwen3.6-27B with SageMaker AI MTRL for multi-turn search agent
- nDCG@10 improved up to 23.7% on BrowseComp-Plus, failure rate fell to 0.68%
- Serverless training with default PPO/CISPO algorithms, per-token pricing

## Why it matters

Shows enterprises can build reliable, low-cost search agents by fine-tuning smaller models with multi-turn RL instead of relying on expensive frontier models.

## Sources

1. [Fine-tune a search agent with multi-turn RL on Amazon SageMaker AI](https://aws.amazon.com/blogs/machine-learning/fine-tune-a-search-agent-with-multi-turn-rl-on-amazon-sagemaker-ai) (AWS Machine Learning Blog, 2026-10-02, primary source)

Part of the developing story: [AWS Expands AI Tools For Search And Conversion](https://digestai.news/thread/aws-shows-how-contextual-bandits-lift-conversions-in-acquisition-funnels) (2 stories)

## Cite

Digest AI, "AWS shows multi-turn RL fine-tuning for search agents on SageMaker AI", 2 October 2026, https://digestai.news/story/aws-shows-multi-turn-rl-fine-tuning-for-search-agents-on-sagemaker-ai

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