Predefined-Tool Execution for Reliable LLM Agents in Semiconductor Lot Analysis

Nirupama Vijayaraghavan Malolan, Duc V. Le


Abstract
LLM agents for structured data analysis rely on dynamic query generation, in which the model synthesises tool calls at runtime. This introduces failures such as fabricated dataset references, unsupported operations, and incorrect results, which existing mitigations reduce but do not eliminate. We propose predefined-tool execution as an architectural alternative in which the language model selects and parameterises tools from a fixed, schema-validated registry. We formalise the approach using typed tool specifications and prove executability and hallucination-suppression properties under assumptions. We complement the architecture with a Numerical Faithfulness Checker that verifies quantitative claims against pre-computed ground truth, and evaluate the system on a domain-specific benchmark using four language-model backbones. The suppression property follows from the validation layer under those assumptions, and held across all 276 evaluated agent executions involving 23 queries, four backbones and three runs. Mean exact-plan-match rates ranged from 50.7 to 53.6 per cent, with a between-backbone spread within a single backbone. Because exact plan match penalises valid but non-minimal plans, it is a strict lower bound on task correctness. Given only three runs per backbone, comparisons are descriptive, not evidence of equivalence The on-premise open-weight backbones performed comparably to commercial ones on the measured metrics, supporting confidential deployments.
Anthology ID:
2026.emnlp-industry.102
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1765–1787
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.102/
DOI:
Bibkey:
Cite (ACL):
Nirupama Vijayaraghavan Malolan and Duc V. Le. 2026. Predefined-Tool Execution for Reliable LLM Agents in Semiconductor Lot Analysis. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 1765–1787, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Predefined-Tool Execution for Reliable LLM Agents in Semiconductor Lot Analysis (Malolan & Le, EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.102.pdf