REVIEW 1 major objections 3 minor 23 references
LLM agent runs leave a persistent disk footprint that is as informative as accuracy and inference cost, and it spans 15.7x across equal-accuracy configurations once measured at the logical-stream level.
Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →
T0 review · deepseek-v4-flash
2026-08-02 06:58 UTC pith:QP5HLF4N
load-bearing objection Storage footprint is a real, measurable evaluation axis; the disclosed boundary caveat is a soft spot, not a fatal one. the 1 major comments →
The Hidden Footprint: Making Storage a First-Class Metric for LLM Agent Evaluation
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The central claim is that persistent storage footprint is a meaningful, orthogonal resource axis for LLM-agent evaluation, and that it has been systematically under-measured because serialization masks duplication. Measuring SQLite cells and JSONL records as logical streams instead of raw bytes raises a naive duplication factor from 1.01 to 12.1 on one store, and content probes confirm the repetition. With this measurement, equal-accuracy configurations differ by 15.7x in retained bytes, the persistence layer alone accounts for a 6.7x spread on identical content, full-history frameworks grow with exponent up to 1.95 on a repeated-observation task, and a content-addressed store reduces retent
What carries the argument
The central object is the six-metric storage-footprint suite (total retention, channel composition, duplication factor D, growth exponent alpha, compressibility C, and 0-3 reconstructability score R), built on a per-run sandbox delta and a serialization-aware meter. The meter extracts logical content streams—SQLite cells and JSONL records—before fingerprinting, so duplication masked by page fragmentation and JSON escaping becomes visible, and content probes estimate how many times input content is stored. A fixed-trace control replays an identical trajectory through each framework's persistence adapter to isolate persistence-layer amplification from agent behavior.
Load-bearing premise
The load-bearing premise is that the fresh-sandbox diff captures every byte the run leaves behind; if significant persistence lands outside the workspace and home boundary (system temp, remote telemetry), the reported totals and spreads shift.
What would settle it
Run the same eight configurations with a full-filesystem container audit covering system temp and remote endpoints; if a configuration's per-task retained bytes outside the declared boundary exceed the reported delta by a meaningful fraction, the metric's attribution boundary fails and the headline spreads need revision.
If this is right
- Benchmark authors can report retained bytes, duplication, growth, compressibility, and reconstructability alongside accuracy and inference cost.
- Equal-accuracy configurations can differ by 15.7x in retained bytes, so a success-only leaderboard hides a large operational difference.
- Full-history persistence grows superlinearly on repeated observations (up to a 1.95 exponent), implying long-running agents need archival policies or windowed context to bound disk usage.
- Content addressing removes 4.8-32.7x of retention while preserving exact conversation-history reconstruction, showing most retained bytes are removable redundancy.
- Exported trajectory volume in the wild shows no detectable correlation with task resolution, so storage volume is not a proxy for quality.
Where Pith is reading between the lines
- If storage becomes a standard reporting axis, frameworks that bundle recovery, audit, and workflow-state capabilities will need capability-normalized efficiency metrics, not just raw byte counts, to be compared fairly.
- The serialization-masking effect generalizes beyond agents: any system persisting structured data via SQLite or JSON is vulnerable to order-of-magnitude duplication that raw byte measurement misses.
- A testable extension: run the same metric suite on long-horizon production workloads with different archival policies to see whether the superlinear growth exponent predicts actual retention obligations at fleet scale.
- The content-addressed reference store suggests delta encoding, not just exact-match deduplication, could close the remaining gap between opaque compression and schema-preserving stores.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. This paper proposes AgentFootprint, a benchmark and metric suite for measuring persistent storage left by LLM agent runs. The six metrics (Stotal, composition, D, α, C, R) are applied in 1,061 sandboxed runs across eight agent frameworks. The controlled study reports a 15.7× spread in retained bytes among 100%-accuracy default configurations, a 6.7× spread under fixed-trace replay, superlinear retention growth for full-history frameworks, zero retention for an in-memory framework, and a 1,617× spread in exported trajectory volume across 108 SWE-bench Verified submissions with no detectable resolve-rate correlation. A content-addressed store reduces retention 4.8–32.7× while preserving reconstructability scores. The paper includes extensive reproducibility artifacts, calibration studies, and sensitivity analyses.
Significance. If the measurements hold, this paper makes a strong case for reporting storage as a resource axis in agent evaluation. Its main methodological contribution is serialization-aware measurement: logical-stream chunking recovers D=12.1 where raw-file chunking sees 1.01, and calibration on synthetic stores confirms the meter on known ground truth. The fixed-trace control cleanly isolates persistence-layer amplification from agent behavior. The empirical effort is unusually careful: exhaustive per-run accounting, a bootstrap CI for the headline spread, two backend replications with rank correlations 0.96/0.89, threshold-sensitivity audits, and an automated verification suite in the artifact. The central claim is credible within the declared sandbox boundary; the open question is whether that boundary fully captures the storage phenomenon the title promises.
major comments (1)
- [§3.2 / Appendix N] The headline numbers all reduce to Stotal, but Stotal is measured only from workspace/HOME snapshots. Appendix N explicitly concedes that the redirected boundary does not cover system temp directories or remote telemetry. The only container validation (§4.3) is LangGraph on three tasks (0–8.5% deviation). For the other seven frameworks, and for LangGraph on the growth stress task, there is no check for writes to /tmp, /var/tmp, SQLite journal directories, or unredirected XDG state. If any framework leaves a few percent of its retention outside the boundary, the 15.7×, 6.7×, and 3.9× spreads and the CAS factors could shift. Because the paper identifies this as an 'extension path,' it is an acknowledged limitation, but it is load-bearing for the central claims. Please extend the container audit to all eight adapters on a representative task set, or provide explicit evidence that none of th
minor comments (3)
- [Appendix B / §3.1] The statement that OpenAI Agents' hosted tracing is disabled because it is remote retention should be moved to §3.1 next to the boundary definition; otherwise readers may not realize Stotal is local-only.
- [§4.2 / references] InfiAgent is the authors' own prior framework; while it is cited, an explicit sentence in the benchmark description would remove any appearance of conflict.
- [Table 1 caption] The caption defines α as a growth exponent but does not state that the value for non-full-history frameworks is a single-run fit while the full-history trio has three seeds; this distinction appears only in the text.
Circularity Check
No circular derivation; measurement-based benchmark with only a minor non-load-bearing self-citation.
full rationale
The paper's derivation chain is self-contained and empirically grounded. The central quantity S_total is defined operationally (§3.1) as bytes present after the run, attributable to it, and absent before it, and is measured by sandbox diffing rather than fitted to any target conclusion. The metrics D, α, C, and R are descriptive or verification-oriented: α is explicitly labeled a descriptive statistic with per-horizon retention primary, and the CAS-reduction claim is verified by re-scoring restored stores rather than assumed. The fixed-trace control replays identical content through seven frameworks and compares measured retained bytes, so the 6.7× spread is a direct measurement, not a consequence of a definition. The in-the-wild trajectory-volume analysis uses public submission metadata and reports a lack of correlation, again purely empirical. There is no fitted parameter that is later renamed as a prediction, no uniqueness theorem imported from the authors' prior work, and no ansatz smuggled in via citation. The only self-citation is the use of InfiAgent, the authors' own framework, as one of eight measured frameworks (§4.2); its footprint is measured in this paper, not taken from the cited prior work, and the headline equal-accuracy 15.7× spread is between LangGraph and CrewAI and does not depend on InfiAgent. The acknowledged boundary limitation in App. N—that the redirected boundary excludes system temp directories and remote telemetry—is a measurement-scope caveat, not a circular step: it affects completeness of S_total but does not make any result equivalent to its inputs by construction. No specific reduction of a claimed result to its own definition or to a self-citation chain can be exhibited.
Axiom & Free-Parameter Ledger
free parameters (4)
- α growth exponent =
LangGraph 1.74±0.01, AutoGen 1.95±0.18, LlamaIndex 1.88±0.10, Agno 0.98, OpenAI Agents 0.73, etc.
- 64B logical-stream length threshold =
64 bytes
- CAS blob size threshold =
1 KB
- zstd compression configuration for C =
zstd-19 with 128MB long-range window
axioms (5)
- domain assumption Per-run fresh-sandbox workspace/home diff captures all task-attributable bytes.
- domain assumption A baseline file with unchanged size is treated as unchanged.
- domain assumption Serialization semantics are invariant across tasks at a fixed framework version and configuration.
- domain assumption Each framework's documented durable-session configuration represents its default persistence behavior.
- standard math FastCDC with SHA-256 exact-match fingerprinting is a sufficient definition of duplication for the paper's claims.
read the original abstract
LLM agent benchmarks measure task completion, reliability, and inference cost, but not the persistent data an agent run leaves on disk, including logs, context snapshots, checkpoints, and debug traces. We introduce AgentFootprint, a cross-framework benchmark of post-run agent storage footprint. Its serialization-aware metric suite measures total retention, channel composition, duplication, growth, compressibility, and conversation-history reconstructability. It addresses a measurement trap: naive byte-level measurement understates duplication by an order of magnitude because database paging and JSON escaping obscure repeated content. A fixed-trace control separates agent-generated logical volume from persistence-layer amplification: replaying the same trajectory through seven persisting frameworks yields a 6.7x spread. Under identical models, tools, and tasks, configurations with 100% accuracy differ by 15.7x in retained bytes, although their defaults support different recovery and audit capabilities. Three full-history configurations grow superlinearly on a repeated-observation stress task. Exported trajectories from 108 instance-normalized SWE-bench Verified submissions span three orders of magnitude per instance, with no detectable correlation with resolve rate. A content-addressed store reduces retention by 4.8x-32.7x while preserving every reconstructability score. These results establish persistent storage as a resource metric to report jointly with accuracy and reconstructability.
Figures
Reference graph
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