Mem2ActBench: A Benchmark for Evaluating Long-Term Memory Utilization in Task-Oriented Autonomous Agents

AuthorsYiting Shen, Kun Li, Wei Zhou, Songlin Hu

2026

TL;DR

Mem2ActBench builds long conversational Fact Evolution Chains and reverse-generated tool calls to show that oracle retrieval boosts F1 from 30.7 to 53.8 on memory-driven tasks.

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THE PROBLEM

Agents fail to apply long term memory in tool use despite 91.3 percent tasks needing it

Existing long term memory benchmarks mostly test explicit fact retrieval instead of memory driven task execution with tools.

Mem2ActBench shows that 91.3% of its 400 tool use tasks are strongly memory dependent, yet agents still misground parameters and misapply historical constraints.

HOW IT WORKS

Mem2ActBench — memory driven tool grounding benchmark

Mem2ActBench builds on Heterogeneous Data Integration, Fact Extraction and Grouping, Memory Evolution Chain Construction, and Memory-anchored Q&A Construction to synthesize realistic long term sessions.

Think of Mem2ActBench as constructing a card catalog of evolving facts, then asking agents to fill tool forms using only the catalog rather than a short clipboard.

By enforcing reverse implicit query generation and leakage detection, Mem2ActBench enables testing memory application that a plain context window benchmark cannot capture.

DIAGRAM

Memory driven tool call generation flow

This diagram shows how Mem2ActBench turns a memory evolution chain into underspecified user queries and grounded tool calls for evaluation.

DIAGRAM

Mem2ActBench dataset construction pipeline

This diagram shows how Mem2ActBench integrates ToolACE, BFCL, and Oasst1 into globally consistent memory evolution chains and memory dependent tasks.

PROCESS

How Mem2ActBench Handles a Memory anchored Tool Use Session

  1. 01

    Heterogeneous Data Integration

    Mem2ActBench merges ToolACE and BFCL task oriented dialogues with Oasst1 conversational noise, creating long interrupted sessions for downstream Fact Extraction and Grouping.

  2. 02

    Fact Extraction and Grouping

    Mem2ActBench prompts an LLM to extract attribute fact source triples and clusters attributes with BERTopic, preparing consistent groups for Memory Evolution Chain Construction.

  3. 03

    Memory Evolution Chain Construction

    Mem2ActBench performs local conflict resolution and global evolution sequence construction using a dependency graph and modified Kahns algorithm to build a coherent Fact Evolution Chain.

  4. 04

    Memory anchored Q and A Construction

    Mem2ActBench selects target tools, anchors parameters to the memory chain, and applies reverse implicit query generation with leakage detection to produce 400 memory dependent tasks.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Inference driven memory utilization benchmark design

    Mem2ActBench formalizes inference driven long term memory utilization by combining Heterogeneous Data Integration and Memory Evolution Chain Construction into 2,029 dialogue sessions with evolving constraints.

  • 02

    Mem2ActBench dataset release

    Mem2ActBench releases 400 memory dependent tool use tasks derived from 2,029 sessions, with human verification showing 91.3 percent of tasks require long term memory.

  • 03

    Comprehensive evaluation of memory frameworks

    Mem2ActBench evaluates seven memory frameworks including LTMemory, A mem, Generative Agents, SCM, Langmem, MemTree, and Mem0, revealing a 23.1 F1 gap between passive and oracle retrieval.

RESULTS

By the Numbers

F1

53.8

+23.1 over Hybrid passive retrieval at k=5

BLEU

53.7

vs Hybrid passive retrieval BLEU 29.7

Tool Accuracy

97.00

Mem0 with Qwen2.5 32B on Mem2ActBench

Memory Dependency Validity

91.3%

expert verified tasks requiring long term memory

Mem2ActBench evaluates memory grounded tool call generation with F1, BLEU, and Tool Accuracy on 400 tasks, showing oracle retrieval F1 53.8 versus best passive hybrid retrieval F1 30.7 and confirming strong memory dependence in 91.3 percent of tasks.

BENCHMARK

By the Numbers

Mem2ActBench evaluates memory grounded tool call generation with F1, BLEU, and Tool Accuracy on 400 tasks, showing oracle retrieval F1 53.8 versus best passive hybrid retrieval F1 30.7 and confirming strong memory dependence in 91.3 percent of tasks.

BENCHMARK

Experimental results for different memory methods across multiple model sizes

Average F1 on Mem2ActBench across Qwen2.5 model sizes for representative memory frameworks.

KEY INSIGHT

The Counterintuitive Finding

Mem2ActBench shows that oracle retrieval boosts F1 from 30.7 to 53.8, a 23.1 point gain over the best passive hybrid retriever.

This is surprising because many assume larger Qwen2.5 backbones solve memory issues, yet Mem2ActBench reveals retrieval quality, not model scale, dominates performance.

WHY IT MATTERS

What this unlocks for the field

Mem2ActBench enables precise diagnosis of where long term memory pipelines fail, separating retrieval misses, mid context loss, and parameter grounding errors in tool use.

With Mem2ActBench, builders can now stress test agent memory managers on realistic, interruption heavy sessions and design retrieval and grounding strategies explicitly targeting mid context and default value failures.

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