What binds large language models on auditable, hypothesis-driven decision tasks, where every candidate can be checked against the evidence? On the public TCMEval-SDT benchmark for Traditional Chinese Medicine syndrome differentiation (200 cases), the binding constraint is output discipline and reasoning structure, not model capability alone: two years of model scaling move zero-shot scores by only -0.03 to +0.08, while output-discipline failures (non-terminating reasoning, format non-compliance, large run-to-run spread) persist even in frontier models. We test this with a model-agnostic agent framework formalizing decision making as a five-stage closed loop, enforced by a candidate x evidence matrix falsification protocol: every candidate is judged against every evidence item, at least half of the candidates must be falsified before a conclusion is licensed, and survivors are emitted in a machine-verifiable single-line format. Across five base models, the effect is sign-conditional on zero-shot output discipline: it rescues models whose discipline fails (DeepSeek-V4-Flash: +0.267/+0.271, entirely termination rescue), reduces a high-variance model's run-to-run standard deviation from 0.218 to 0.007 (Kimi K3), and significantly costs already-disciplined models (-0.087 to -0.120 on budget-matched Qwen3-4B/32B). Ablations attribute the cost to the candidate-bounded format layer and show the effect is independent of injected knowledge content (protocol-knowledge decoupling). The protocol also transfers to misinformation-robust mathematical reasoning, detecting injected false premises at 89.8% recall with a 6.8% false-positive rate (MCC 0.54; a flag-everything baseline scores 0) and restoring accuracy to the no-misinformation ceiling. Where zero-shot output discipline is weak, the reasoning protocol sets the floor; base-model capability always sets the ceiling.
Figures & tables
Figure 1: Four-layer architecture. The epistemic layer defines the hypothesis–verification–causal-analysis–action loop; the TCM process layer carries the differentiation workflow, closing the loop through the validation-feedback stage; the model layer (LLM-1/LLM-2/ML/RAG) executes it; the data layer holds syndrome–sign mappings, reasoning data, case mappings, and safety rules. Within the process layer, verification takes the form of targeted questioning over typical sign–syndrome data, and causal analysis proceeds over the five-phase self-consistent system.
Figure 2: End-to-end processing pipeline (S1–S9) with anti-deadlock questioning guards, the insufficiency re-examination loop after matrix falsification, and prescription-violation interception.
Figure 3: The candidate × four-examination evidence matrix falsification protocol on a worked example. Three knowledge inputs build the matrix; row-level aggregation yields compatibility verdicts; the sufficiency check requires at least half of the candidates to be incompatible, otherwise evidence is re-examined; the most-supported compatible candidate is emitted in the single-line protocol format.
Method stage
Lifecycle state(s)
Intent triage, direct retrieval
outside the machine
Information collection, sufficiency
COLLECT
Hypothesis & evidence construction
DIAGNOSE (prompt injection)
Matrix falsification & output
DIAGNOSE (output protocol)
Causal-chain reasoning
DIAGNOSE (reasoning)
Action: plan, prescribe, review
PLAN → PRESCRIBE → REVIEW
Table 1: Mapping between method stages and lifecycle states.
Figure 4: Official-script scores on TCMEval-SDT (our own runs, n=200 per task). Paired bars show zero-shot vs. +agent for each base model; error bars mark the standard deviation over three repetitions where available. Dashed lines mark the benchmark paper’s best reported zero-shot baselines (2023–2024 era, 50-case subset). Note the K3 pair: the zero-shot error bar ( ±0.218 , descriptive spread over the n=3 runs) versus the agent’s ( ±0.007 ) is the visual evidence for the stabilization claim—the protocol reduces run-to-run standard deviation by an order of magnitude (point estimate 31-fold).
Model
Variant
Syndrome
Pathogen.
Qwen3-4B
zero-shot
0.481 ± 0.005
0.455 ± 0.010
Qwen3-4B
+ agent
0.365 ± 0.013
0.335 ± 0.010
PT-4B
zero-shot
0.473 ‡
0.457 ‡
PT-4B
+ agent
0.362 ‡
0.345 ‡
Qwen3-32B
zero-shot
0.551 ± 0.007
0.523 ± 0.006
Qwen3-32B
+ agent
0.464 ± 0.011
0.411 ± 0.009
Table 2: Official-script scores on TCMEval-SDT (our own runs, n=200 per task). Values are mean ± std over 3 repetitions; † marks single runs; ‡ marks single budget-matched greedy runs (8,192-token budget). Paper baselines are 2023–2024-era zero-shot on a 50-case subset, converted to per-case means. Bold values mark per-column maxima; the bold row label marks the protocol configuration.
Syndrome
Pathogen.
Model
Variant
EM
F1
hit
EM
F1
hit
Qwen3-4B
zero
20.0
0.588
87.0
9.5
0.578
92.5
Qwen3-4B
agent
16.5
0.465
70.0
7.0
0.425
72.5
PT-4B
zero
17.5
0.589
89.0
8.0
0.585
92.5
PT-4B
agent
15.0
0.444
67.0
8.5
0.452
77.0
Qwen3-32B
zero
29.7
0.644
88.0
16.7
0.636
92.0
Table 3: Auxiliary metrics (n=200 per task, C2/C3 campaigns as in Table 2 ): exact match (EM, %), macro-F1, and set hit rate (%). The hit–score gap quantifies the over-prediction failure mode of Section 5.7 : high hit with a modest official-script score indicates over-selection (e.g., 4B zero-shot: 87.0% hit vs. 0.481 score).
Model
Task
Answer rate (%)
Over-pred.
Run std
Cross-run agr. (%)
Δ
DS-Flash
syn.
38.5
0.42
0.015
60.0
+0.267
DS-Flash
pat.
33.0
0.42
0.012
62.5
+0.271
DS-Pro
syn.
62.5
0.75
—
—
+0.094
DS-Pro
pat.
51.0
0.66
—
—
+0.210
K3
syn.
99.5
1.38
0.218
10.5
+0.080
K3
pat.
97.0
1.43
0.043
37.0
−0.032
Table 4: Output-discipline profile of each base model, measured on protocol-free zero-shot outputs (200 cases per task), against the protocol’s gain Δ (agent − zero-shot; CIs and p -values in Table 5 ). Answer-extraction rate : fraction of cases whose output yields a machine-extractable answer under the benchmark’s official extraction rule, computed on the first repetition of each arm (DS-Pro’s only repetition), so the rate is comparable across arms—for thinking models this coincides with termination within budget, and it subsumes format non-compliance. Over-prediction ratio : per-case mean of ∣pred∣/∣gold∣ . Run std : standard deviation of run means across three repetitions. Cross-run agreement : fraction of cases with identical predicted label sets across all three runs. Run std and self-consistency require three repetitions and are unavailable for the single-run zero-shot configuration (DS-Pro).
Figure 5: The protocol’s gain against the zero-shot answer-extraction rate, per base model and task. Each model the protocol helps carries a distinct measurable failure mode (non-termination for flash, partial non-termination for Pro, instability for K3); the two models it hurts show none. Rank correlations are reported qualitatively at n=5 .
Model
Task
Δ
95% CI
p (case)
p (run)
Qwen3-4B
syndrome
− 0.116
[ − 0.167, − 0.064]
2.6e-05
1.7e-03
Qwen3-4B
pathogen.
− 0.120
[ − 0.157, − 0.084]
8.1e-10
1.0e-04
DS-Flash
syndrome
+0.267
[+0.226, +0.307]
6.1e-22
1.3e-02
DS-Flash
pathogen.
+0.271
[+0.234, +0.307]
2.0e-24
6.7e-02
DS-Pro
syndrome
+0.094
[+0.039, +0.149]
4.2e-03
—
DS-Pro
pathogen.
+0.210
[+0.131, +0.295]
1.4e-12
—
Table 5: Paired tests of the mechanism’s gain (zero-shot → +agent) per base model and task: per-case mean difference Δ with bootstrap 95% CI and Wilcoxon p (n=200 cases). Raw p -values; the family-wise Bonferroni threshold for this 10-test family is 0.005. The Qwen3-4B comparison is budget-matched (both sides greedy with an 8,192-token budget, three repetitions each on the same vLLM backend). DS-Pro rows are single-repetition (case-level tests only) and are descriptive under the two-level standard of Section 4.4 . The 4B negative result cannot be attributed to truncation. Run-level p : conservative replication check—Welch’s t -test over the three run means per side (Section 4.4 ), uncorrected; “—” for configurations with a single-run side.
Model
Subset
n
Zero
Agent
Δ (95% CI)
p
DS-Flash syn.
full
200
0.289
0.556
+0.267 [ +0.226,+0.307 ]
6.1e-22
reliably terminating
43
0.866
0.781
−0.085 [ −0.133,−0.037 ]
2.0e-03
rescue-prone
157
0.132
0.494
+0.363 [ +0.325,+0.401 ]
2e-25
DS-Flash pat.
full
200
0.212
0.482
+0.271 [ +0.233,+0.308 ]
2e-24
reliably terminating
32
0.709
0.622
−0.087 [ −0.140,−0.034 ]
3.1e-03
rescue-prone
168
0.117
0.456
+0.339 [ +0.304,+0.374 ]
4e-27
Table 6: Rescue/terminating decomposition of the zero-shot → agent gain on the DeepSeek models (paired per-case differences, 95% CI, Wilcoxon p ). Reliably terminating : zero-shot yields an extractable answer in every repetition (DS-Pro: single run)—a strictly stronger condition than the per-repetition answer-extraction rate of Table 4 , which is why the flash subset (43/200 cases) is smaller than that rate (38.5%) suggests. Rescue-prone : the complement. K3 and the Qwen models terminate at ≥ 97% zero-shot answer rate, so for them the full-set contrast in Table 5 is already a terminating-case estimate. For DS-Pro the agent-side budget is 16,384 tokens and roughly half of its terminating case-runs exceed the 8k-equivalent line, so its rescue-prone gains retain a budget component that the post-hoc proxy (Appendix F ) can only partially exclude. DS-Pro rows are single-repetition and hence descriptive under the two-level standard of Section 4.4 . Full-set rows duplicate Table 5 for readability.
Arm (content / matrix / format)
Syn.
Pat.
Hit syn./pat. (%)
zero-shot ( − / − / − )
0.481 ± 0.005
0.455 ± 0.010
87.5 / 92.0
format only ( − / − /+)
0.240
0.172
38.0 / 38.0
content only (G1, +/ − / − )
0.388 ± 0.009
0.319 ± 0.007
59.0 / 66.7
no matrix (G5, +/ − /+)
0.392 ± 0.007
0.343 ± 0.004
67.3 / 72.8
no format (G6, +/+/ − )
0.334 ± 0.007
0.284 ± 0.002
67.5 / 70.5
full protocol (+/+/+)
0.365 ± 0.013
0.335 ± 0.010
67.5 / 74.2
Table 7: The completed three-factor factorial on budget-matched Qwen3-4B (three repetitions per arm, n=200 per task). The content bundle is knowledge injection + causal chain; “format” is the candidate-bounded single-line emission mandate; “matrix” is the falsification-matrix requirement.
Official-script score
Δ vs. G0 (CI, p )
Hit Δ (pp)
Group
Syn.
Pat.
Syn.
Pat.
Syn.
Pat.
G0 full agent
0.365 ± 0.013
0.335 ± 0.010
—
—
67.5
74.2
G1 − matrix+format block
0.388 ± 0.009
0.319 ± 0.007
+0.022 (n.s.)
−0.015 (n.s.)
−8.5
−7.5
G2 − evidence checklist
0.403 ± 0.009
0.332 ± 0.004
+0.038 (n.s.)
−0.003 (n.s.)
+6.2
−1.6
G3 − diff. guide
0.391 ± 0.018
0.347 ± 0.015
+0.026 (n.s.)
+0.012 (n.s.)
+2.2
−0.7
G4 − all skill knowledge
0.364 ± 0.009
0.353 ± 0.004
−0.001 (n.s.)
+0.019 (n.s.)
+11.9
+4.8
Table 8: Component ablations (Qwen3-4B, C3 budget-matched greedy configuration, 8,192-token budget, vLLM; three repetitions per group, n=200 per task). Official score mean ± std; Δ and hit-rate change vs. G0 (paired Wilcoxon; n.s. = p>0.05 ).
Model
Configuration
Syn.
Pat.
Qwen3-4B
zero-shot
0.481 ± 0.005
0.455 ± 0.010
Qwen3-4B
CoT (greedy)
0.487 ± 0.004
0.471 ± 0.005
Qwen3-4B
self-consistency ( t=0.7 )
0.479
0.405
Qwen3-4B
+ agent (full protocol)
0.365 ± 0.013
0.335 ± 0.010
K3
zero-shot
0.496 ± 0.218
0.556 ± 0.043
K3
self-consistency ( t=1.0 )
0.631
0.596
Table 9: Standard reasoning baselines vs. the agent (same-model, official-script score; three repetitions). K3 self-consistency uses the existing temperature-1.0 repetitions; 4B self-consistency samples at temperature 0.7.
κ
Syndrome
Pathogen.
Δ syn.
Δ pat.
p (pat.)
41
0.368
0.333
−0.012
+0.010
n.s.
21 (deployed)
0.380
0.323
—
—
—
43
0.403
0.361
+0.024
+0.037
0.036
Table 10: Stopping-fraction ablation (Qwen3-4B, budget-matched greedy, 8,192-token budget, vLLM; n=200 per task, one repetition per κ ). Official scores; Δ and p vs. the deployed κ=21 (paired Wilcoxon with bootstrap CI). The κ=21 row is a single run of the G0 configuration and sits within G0’s three-repetition run-to-run spread ( 0.365±0.013 syndrome, Table 8 ); the within-table Δ contrasts are unaffected since all three κ arms share the same single-repetition protocol.
Property
Internalized reasoning
External protocol (ours)
Manipulation resistance
effective [ 26 , 27 ]
ceiling-restoring, > instruction (Sec. 5.6 )
Cross-model transfer
no (bound to training)
yes (model-agnostic adapter)
Auditability
black-box
white-box (cell-level logs)
Failure mode
error entrenchment [ 27 ]
over-prediction (Sec. 5.7 )
Correctability
not evidence-revisable
re-examination loop
Table 11: Two defense mechanisms against manipulation of reasoning. Our protocol targets the right-hand column; the misinformation-benchmark evaluation is reported in Section 5.6 .
Appendix figures & tables1 asset
Supplementary material from the paper’s appendix.
Appendix
Certification
task
n
zero-shot
agent
Δ [95% CI]
Wilcoxon p
strict
syn.
17
0.183
0.647
+0.464 [ +0.332 , +0.597 ]
3e-4
strict
pat.
7
0.089
0.326
+0.237 [ +0.140 , +0.335 ]
0.036
typical
syn.
136
0.138
0.507
+0.369 [ +0.327 , +0.411 ]
4e-22
typical
pat.
87
0.136
0.535
+0.399 [ +0.350 , +0.449 ]
2e-15
Appendix
Table 12: Budget-certified rescue-prone subsets (DS-Flash, C2; paired per-case differences on the run-mean official score). Strict : agent terminates below the rate-free bound (66.9 s/64.6 s) in every repetition. Typical : agent terminates in every repetition with the median repetition below the bound.
State Key Laboratory of Internet of Things for Smart City and Institute of Smart City Technologies, University of Macau, Macau SAR, China · ByteDance, Beijing, China
MIT Critical Data, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States · Georgia State University, Atlanta, Georgia, United States · Politecnico di Milano, Milan, Italy +12