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arxiv: 2606.03135 · v1 · pith:CV3JV5CEnew · submitted 2026-06-02 · 💻 cs.AI

Uncertainty-Aware Clarification in LLM Agents with Information Gain

Pith reviewed 2026-06-28 10:25 UTC · model grok-4.3

classification 💻 cs.AI
keywords LLM agentsclarificationinformation gainBayesian belief updateuncertainty resolutiontask successtool use
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The pith

LLM agents improve task success by training clarifiers on information gain toward the user's true goal.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper shows that LLM agents facing underspecified instructions can reduce errors by asking clarification questions whose value is scored by how much they shift a Bayesian belief distribution closer to the actual user goal. A reward function built on this information-gain measure is used to train the clarifier so that it produces questions that measurably raise downstream task completion rates. Experiments in a clarification-augmented environment across five different model backbones report a 3.7 percent success-rate lift while adding only 0.3 interaction steps on average. The approach therefore treats clarification as an explicit optimization step rather than an ad-hoc addition to the agent loop.

Core claim

A reward defined by the Bayesian belief update toward the ground-truth goal allows an LLM clarifier to be trained so that its questions reduce uncertainty enough to raise agent success rates in ambiguous tool-use settings.

What carries the argument

The Information Gain Reward, which scores each clarification exchange by the size of the Bayesian shift it produces in the agent's belief distribution over possible user goals.

If this is right

  • Agents achieve higher completion rates on tasks whose instructions contain latent ambiguity.
  • The performance gain holds across heterogeneous LLM backbones without per-model redesign.
  • The added cost of clarification remains small, measured at roughly one-third of an extra turn on average.
  • Clarification behavior becomes an optimizable component inside the agent-tool-user loop rather than a separate heuristic.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same reward could be attached to other agent training loops that already use belief tracking.
  • Real-world deployments might see fewer tool-call failures when instructions are vague.
  • The method suggests that uncertainty measures derived from posterior updates can serve as general training signals for interactive agents.

Load-bearing premise

That the size of the Bayesian belief update produced by a clarification question reliably predicts whether that question will increase the agent's chance of completing the task.

What would settle it

An experiment in which agents using the information-gain-trained clarifier achieve equal or lower success rates than agents that never clarify, or in which the measured belief updates show no correlation with actual task outcomes.

Figures

Figures reproduced from arXiv: 2606.03135 by Mengyi Deng, Tingyu Zhu, Wei Wang, Xin Li, Ying Zhao, Zhijiang Guo, Zhiwei Li.

Figure 1
Figure 1. Figure 1: An example of clarification in a τ -retail trajectory. When an initial tool call fails due to missing or underspecified informa￾tion, the Clarifier poses a targeted follow-up question (highlighted) to elicit the required constraints from the user. The additional information provided through this exchange allows the agent to proceed with a corrected tool invocation and complete the task. contexts, however, … view at source ↗
Figure 2
Figure 2. Figure 2: Overview of the Amortized Bayesian Experimental Design framework. The model performs on-policy sampling to generate candidate questions. These candidates are evaluated by our Belief Update Reward, which quantifies efficacy as the shift in the teacher￾forced log-likelihood of the ground-truth goal G ∗ (Bayesian Belief Update). Acting as an amortized surrogate for the intractable expected information gain, t… view at source ↗
Figure 3
Figure 3. Figure 3: Training dynamics of DAPO under the information gain reward objective. questions {Q(k)} K k=1, and A(k) is the response returned by the strict user simulator for the sampled question Q(k) . The empirical average of their rewards provides an unbiased estimate of the expected utility: U(θ) ≈ EQ∼πθ [Rt] ≈ 1 K X K k=1 Rt(xt, Q(k) , A(k) ). (3) As training progresses, πθ increasingly concentrates proba￾bility m… view at source ↗
Figure 4
Figure 4. Figure 4: Effect of clarification budget on task success and interaction efficiency under forced sampling. leads to a substantial performance degradation, especially on the airline domain, where success rate falls from 17.3% to 10%, suggesting that conditional likelihood alone is in￾sufficient to encourage informative clarifications in domains. The LLM-as-a-judge variant further exhibits unstable behav￾ior: although… view at source ↗
Figure 6
Figure 6. Figure 6: Policy Entropy During DAPO Training [PITH_FULL_IMAGE:figures/full_fig_p020_6.png] view at source ↗
read the original abstract

Large Language Model (LLM) agents often operate under underspecified user instructions, where latent uncertainty over user intent leads to erroneous tool actions. To address this challenge, we propose a goal-oriented clarification framework that aligns clarification behavior with ambiguity resolution. Central to our approach is the Information Gain Reward, a metric that quantifies the utility of clarification questions by measuring the Bayesian belief update towards the ground-truth goal induced by the clarification exchange. We train the clarifier (LLM) using this reward to optimize for high information gain, ensuring that clarifications effectively reduce uncertainty and improve task completion within the agent-tool-user environment. We validate our framework within a clarification-enhanced $\tau$-Bench environment, conducting cross-agent evaluations across five heterogeneous backbones. Empirical results demonstrate that our method consistently improves the success rate by 3.7\% over the no-clarification baseline, while adding only 0.3 total interaction steps on average.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper proposes a goal-oriented clarification framework for LLM agents that uses an Information Gain Reward, defined as the reduction in uncertainty over a ground-truth goal via Bayesian belief update, to train a clarifier LLM. It evaluates the approach in a clarification-enhanced τ-Bench environment across five heterogeneous agent backbones and reports a consistent 3.7% success-rate improvement over a no-clarification baseline while adding only 0.3 interaction steps on average.

Significance. If the Information Gain Reward is shown to correlate with downstream task success, the framework could offer a principled, uncertainty-aware method for handling underspecified instructions in LLM agents. The cross-backbone evaluation design is a positive feature that would strengthen generalizability claims if supported by detailed statistics.

major comments (3)
  1. [Abstract] Abstract: the central claim of a consistent 3.7% success-rate gain is presented without error bars, statistical tests, per-backbone breakdowns, or variance measures, preventing verification of whether the improvement is robust or attributable to the proposed reward.
  2. [Empirical results] Empirical results section: no ablation replaces the Information Gain Reward with random or heuristic rewards, and no per-question correlation is reported between achieved IG values and subsequent success deltas; without this, the performance gain cannot be attributed to the Bayesian-update objective rather than incidental effects of clarification.
  3. [Information Gain Reward definition] Information Gain Reward definition: the reward is computed toward a ground-truth goal available only during training; the manuscript does not demonstrate that the resulting clarifier generalizes when ground-truth is unavailable at inference time, which is required for the method to be applicable beyond simulation.
minor comments (2)
  1. [Methods] Clarify the exact form of the Bayesian update (prior, likelihood model, and posterior computation) and whether it assumes access to the agent's internal state.
  2. [Experimental setup] The τ-Bench environment modifications for clarification should be described with sufficient detail to allow reproduction.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their insightful comments, which have helped us identify areas to strengthen the paper. We provide point-by-point responses below.

read point-by-point responses
  1. Referee: [Abstract] Abstract: the central claim of a consistent 3.7% success-rate gain is presented without error bars, statistical tests, per-backbone breakdowns, or variance measures, preventing verification of whether the improvement is robust or attributable to the proposed reward.

    Authors: We agree that providing error bars, statistical tests, and per-backbone breakdowns would enhance the verifiability of our claims. In the revised manuscript, we will include these details in the empirical results section and update the abstract to reference the robustness of the improvement across models. We will also report variance measures and conduct appropriate statistical tests to confirm the significance of the 3.7% gain. revision: yes

  2. Referee: [Empirical results] Empirical results section: no ablation replaces the Information Gain Reward with random or heuristic rewards, and no per-question correlation is reported between achieved IG values and subsequent success deltas; without this, the performance gain cannot be attributed to the Bayesian-update objective rather than incidental effects of clarification.

    Authors: We recognize the importance of ablations to attribute the gains specifically to the Information Gain Reward. We will incorporate additional experiments in the revised version that replace the Information Gain Reward with random and heuristic alternatives. Furthermore, we will analyze and report correlations between achieved information gain values and success rate improvements on a per-question basis to strengthen the causal link to our proposed objective. revision: yes

  3. Referee: [Information Gain Reward definition] Information Gain Reward definition: the reward is computed toward a ground-truth goal available only during training; the manuscript does not demonstrate that the resulting clarifier generalizes when ground-truth is unavailable at inference time, which is required for the method to be applicable beyond simulation.

    Authors: The Information Gain Reward is utilized solely during the training of the clarifier to learn an effective policy. Once trained, the clarifier functions at inference time without requiring access to the ground-truth goal, as it has internalized the patterns for generating high-utility clarification questions. We will revise the manuscript to explicitly clarify this training-inference distinction and add an evaluation demonstrating the clarifier's effectiveness in scenarios where ground-truth information is not provided during inference, thereby addressing applicability beyond simulation. revision: yes

Circularity Check

0 steps flagged

No circularity; Information Gain Reward defined from standard external Bayesian update with independent empirical validation.

full rationale

The paper's central construction defines the Information Gain Reward directly via Bayesian belief update toward a ground-truth goal, a standard external concept with no reduction to the paper's fitted outputs or self-referential loop. Empirical success-rate gains are measured against an external no-clarification baseline in the τ-Bench environment across heterogeneous agents; no equations or claims reduce a prediction to a fitted parameter by construction, and no self-citation is invoked as load-bearing justification. The derivation chain remains self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 1 invented entities

The central claim rests on the assumption that Bayesian belief updates provide a faithful utility signal for clarification; no free parameters or additional invented entities are stated in the abstract. Because only the abstract is available, the ledger is necessarily incomplete.

axioms (1)
  • domain assumption Bayesian belief update toward a known ground-truth goal measures the value of a clarification exchange
    This is the explicit definition of the Information Gain Reward and is required for the training signal.
invented entities (1)
  • Information Gain Reward no independent evidence
    purpose: Quantify utility of clarification questions for training
    New metric introduced to align clarification behavior with ambiguity resolution

pith-pipeline@v0.9.1-grok · 5699 in / 1292 out tokens · 31548 ms · 2026-06-28T10:25:09.738759+00:00 · methodology

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    Your name is

    Can you do that with gift card 7711863? Analysis Redundant Confirmation: The user re-states known preferences. No new entities are introduced. Targeted Elicitation: The agent identifies the missing payment slot and asks for it directly. The user provides the gift card ID. Log Prob (xt) −3.2649 Log Prob (xt, Q, A) −3.3193(%↓) −2.6153(%↑) Reward (Rt) −0.054...