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Deconstructing Instruction-Following: A New Benchmark for Granular Evaluation of Large Language Model Instruction Compliance Abilities

Paper · 2026 · Alberto Purpura, Li Wang, Sahil Badyal et al.

Summary

Current instruction-following benchmarks often use constraints with little practical value, tie constraints to the specific prompt task so that compliance and task success get mixed together, and rarely test more than a handful of instructions at once. To tackle these issues, the authors introduce MOSAIC, a benchmark built through dynamic generation, whose name reflects a modular and synthetic approach to evaluating instruction compliance. Each prompt combines one of four business writing tasks, one of eight products or services, and a list of 1 to 20 constraints sampled from a pool of 21 application-oriented rules. Because the constraints are a separate, reusable module, they can be paired with other tasks, and regenerating the data guards against leakage. Rule-checkable constraints are scored automatically. Semantic and business/legal constraints are scored by an LLM judge that was validated against human annotators. The evaluation covers models from several families, including Llama, Qwen3, Deepseek, Mixtral, Gemini and Claude. It shows that compliance depends strongly on the type, number and position of constraints. It also reveals helpful and conflicting interactions between instructions, as well as model-specific positional biases. These diagnostics help pinpoint failures in systems that require strict rule adherence.

Key points

  • The dataset has 4,000 prompts averaging 10.5 constraints each, which is more than double the density of benchmarks like ComplexBench, IFEval or InFoBench. Prompts average about 222 words, and the constraints span 5 groups and 21 types.
  • The tasks are a marketing email, a product review, an FAQ entry and an internal memo. Crossed with 8 product/service types, they give 32 generation variants.
  • Constraint position matters in different ways for different models:
    • Llama, Qwen3 and Deepseek show a primacy effect, following early constraints more reliably.
    • Mixtral-8x-7B, Gemini and Claude favor later constraints, a recency effect.
    • Claude and Gemini spike sharply at position 19 and then drop at position 20.
  • The number of constraints also shapes compliance:
    • With 1–6 constraints, Qwen3 is the most compliant model.
    • Between 7 and 15 constraints, results become erratic for all models.
    • Beyond 15, compliance falls for nearly all models, most sharply for reasoning models such as Deepseek-R1 8b and Qwen3.
  • The code is public (CapitalOne-Research/llm-instruction-following-compliance on GitHub). Prompts are English only, but the authors suggest automatic translation could extend the benchmark to other languages, such as Ukrainian.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

 Fields, topics and concepts

Cite

Cite as Alberto Purpura, Li Wang, Sahil Badyal, Gene Beaufrand and Adam Faulkner. 2026. Deconstructing Instruction-Following: A New Benchmark for Granular Evaluation of Large Language Model Instruction Compliance Abilities. Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers).

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.eacl-long.62

@inproceedings{purpura2026deconstructing,
  title = {{Deconstructing Instruction-Following: A New Benchmark for Granular Evaluation of Large Language Model Instruction Compliance Abilities}},
  author = {Alberto Purpura, Li Wang, Sahil Badyal, Gene Beaufrand and Adam Faulkner},
  booktitle = {Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)},
  year = {2026},
  doi = {10.18653/v1/2026.eacl-long.62},
  url = {https://doi.org/10.18653/v1/2026.eacl-long.62}
}

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