UTILMEM: Benchmarking Evidence Utilization in Long-Term Conversational Memory

AuthorsPeijun Qing, Fobo Shi, Soroush Vosoughi

arXiv 20262026

TL;DR

UTILMEM uses evidence-sensitive question filtering plus adversarial distractor haystacks to show that NaiveRAG only reaches 59.3 NR with 49.2 DR despite strong factual recall.

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THE PROBLEM

Memory benchmarks miss utilization gaps despite 1,717 evidence-sensitive tasks

Existing long-term memory benchmarks mostly test pointwise factual recall, not whether agents can use distributed, implicit, and noisy evidence across sessions.

UTILMEM shows that systems with strong recall still fail on dense multi-session reasoning, implicit retrieval, and distractor filtering, leading to degraded long-form guidance and plans.

HOW IT WORKS

UTILMEM construction pipeline for evidence utilization

UTILMEM builds on four core components: Evidence Synthesis, Question Generation, Evidence-Sensitivity Filtering, and Haystack Construction to create 1,717 utilization-focused instances.

You can think of UTILMEM as a memory stress lab: it loads the “disk” with realistic histories, then tests how well agents pull the right “cards” from a noisy catalog.

This design lets UTILMEM expose failures that a plain context window or recall-only benchmark cannot, especially under adversarial distractors and long-form composition.

DIAGRAM

UTILMEM evaluation flow for memory utilization

This diagram shows how UTILMEM evaluates memory systems by comparing noisy-history answers against oracle-evidence answers with rubric LLM judges.

DIAGRAM

UTILMEM benchmark construction stages

This diagram shows UTILMEM’s four-stage construction pipeline from source datasets to adversarial haystack histories.

PROCESS

How UTILMEM Handles a Benchmark Instance Lifecycle

  1. 01

    Evidence Synthesis

    UTILMEM groups source items into multi-session bundles and rewrites them into dialogues, ensuring persona consistency and deduplication across Evidence Synthesis.

  2. 02

    Question Generation

    UTILMEM runs Question Generation over each bundle to create deterministic, multi-session dependent questions that use retrieval-compatible phrasing tied to the conversation text.

  3. 03

    Evidence-Sensitivity Filtering

    UTILMEM applies Evidence-Sensitivity Filtering via sampled removal paths and dual LLM judges, keeping only questions where answer quality strictly degrades from E(1) to E(3).

  4. 04

    Haystack Construction

    UTILMEM performs Haystack Construction by synthesizing adversarial distractors, merging cross-domain sessions, and sorting them into full histories H that stress retrieval robustness.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Benchmark for memory utilization

    UTILMEM introduces 1,717 instances across five domains that jointly target dense multi-session reasoning, implicit retrieval, long-form composition, and distractor filtering.

  • 02

    Scalable synthesis pipeline

    UTILMEM’s pipeline combines Evidence Synthesis, Question Generation, Evidence-Sensitivity Filtering, and Haystack Construction to produce evidence-sensitive, adversarially noisy tasks.

  • 03

    Empirical gap between access and use

    UTILMEM shows systems like Mem0 and Mem0+Graph drop to 18.9 NR with 97.8 DR, revealing that strong factual recall does not guarantee robust memory utilization.

RESULTS

By the Numbers

Normalized Robustness

59.3 NR

+41.9 over Mem0+Graph

Degradation Rate

49.2 DR

-48.6 vs Mem0+Graph

Instances

1,717 tasks

UTILMEM benchmark size across five domains

Domains

5 domains

Learning, Finance, Mental, Fitness, Document

UTILMEM evaluates memory utilization over 1,717 tasks spanning Learning Support, Finance Guidance, Mental Wellness, Fitness Coaching, and Document Analysis. The main result shows NaiveRAG + Qwen3-Embedding-8B retains 59.3% of the oracle robustness score with 49.2% of instances degrading, while Mem0+Graph collapses to 18.9 NR and 97.8 DR, highlighting the cost of compression-heavy memory.

BENCHMARK

By the Numbers

UTILMEM evaluates memory utilization over 1,717 tasks spanning Learning Support, Finance Guidance, Mental Wellness, Fitness Coaching, and Document Analysis. The main result shows NaiveRAG + Qwen3-Embedding-8B retains 59.3% of the oracle robustness score with 49.2% of instances degrading, while Mem0+Graph collapses to 18.9 NR and 97.8 DR, highlighting the cost of compression-heavy memory.

BENCHMARK

Pairwise generation quality against the oracle answer across five domains

Average Normalized Robustness (NR) across all UTILMEM domains for retrieval-only and structured memory systems.

KEY INSIGHT

The Counterintuitive Finding

UTILMEM shows that NaiveRAG with simple turn-level retrieval reaches 59.3 NR, while graph-augmented Mem0+Graph drops to 18.9 NR despite added structure.

This is counterintuitive because builders often assume more structured memory and compression help, but UTILMEM reveals that write-time fact extraction can destroy crucial utilization details.

WHY IT MATTERS

What this unlocks for the field

UTILMEM unlocks a way to stress-test long-term agents on evidence integration, not just recall, under realistic multi-session noise and adversarial distractors.

With UTILMEM, builders can now diagnose whether new memory architectures truly help agents use past interactions for planning, analysis, and coaching, rather than just storing more facts.

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