Preprint
Large Language Models

MANTRA: Synthesizing SMT-Validated Compliance Benchmarks for Tool-Using LLM Agents

May 1, 2026

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2026

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Abstract

… results demonstrate that combining automated benchmark generation with formally grounded validation methods enables scalable and reliable benchmarking of tool-using agents. …

Analysis

Why This Paper Matters

As LLM-based agents increasingly interact with external tools and APIs, the need for reliable evaluation benchmarks becomes critical. Traditional benchmarks are often manually curated, which is time-consuming, costly, and prone to errors. MANTRA addresses this by automating benchmark generation while ensuring quality through formal validation. This is particularly important because tool-using agents can exhibit complex behaviors that are hard to test exhaustively with hand-crafted examples.

The use of SMT solvers for validation is a novel approach in the LLM benchmarking space. SMT solvers provide formal guarantees about the correctness of generated benchmarks, which is a significant step up from heuristic or manual checks. This could set a new standard for benchmark reliability, especially in safety-critical domains where compliance is essential.

Technical Contributions

  • Automated Benchmark Synthesis: MANTRA generates benchmark instances programmatically, covering a wide range of scenarios without manual authoring.
  • SMT-Based Validation: Each generated instance is checked against compliance constraints using SMT solvers, ensuring that the benchmark is logically sound and meets specified requirements.
  • Scalability: The automated pipeline allows for the creation of large-scale benchmarks with minimal human intervention, which is crucial for evaluating modern LLM agents.
  • Reliability: Formal validation reduces the risk of invalid or ambiguous test cases, leading to more trustworthy evaluation results.

Results

The abstract reports that the combination of automated generation and formally grounded validation methods enables scalable and reliable benchmarking. While specific quantitative results are not provided in the abstract, the qualitative outcome is clear: the approach successfully addresses the dual challenges of scale and reliability. This suggests that MANTRA can produce benchmarks that are both extensive and accurate, which is a key requirement for meaningful agent evaluation.

Significance

The broader impact of MANTRA lies in its potential to democratize benchmark creation. By reducing the manual effort and expertise required to build high-quality benchmarks, it enables more research groups to evaluate their agents rigorously. This could accelerate progress in tool-using agent development, as reliable benchmarks are essential for measuring improvements and comparing approaches.

Furthermore, the integration of formal methods into the benchmarking pipeline highlights a growing trend of using rigorous verification techniques in AI evaluation. This could inspire similar approaches in other areas, such as safety testing or adversarial robustness, where formal guarantees are valuable. Overall, MANTRA represents a meaningful step toward more scientific and scalable evaluation of LLM agents.