---
license: mit
language:
- en
pretty_name: tool-failure
size_categories:
- n<1K
task_categories:
- question-answering
tags:
- llm-evaluation
- tool-use
- mcp
- agents
- claude
configs:
- config_name: rows
  data_files:
  - split: train
    path: results.json
  field: rows
---

# tool-failure

Author: Dmitriy Semenkevich (dimhold)

This dataset measures whether a model's answer reports a broken tool: 100 calls through an MCP server written for the study that breaks its own tool in 5 ways, on claude-haiku-4-5 and claude-opus-5.

Headline, from the repository: "When a tool breaks loudly, the model's answer says so 39 times out of 40. When the same tool returns a corrupted value and stays quiet, the answer says so 0 times out of 40."

This is a mirror. The canonical home is the Zenodo record and the GitHub repository; criteria, limitations and full tables live there.

- Paper: https://dimhold.by/papers/tool-failure/
- Code and full write up: https://github.com/dimhold/tool-failure
- DOI: https://doi.org/10.5281/zenodo.22128837

## Files

| path | what it is |
|---|---|
| `results.json` | structured output of all 100 calls joined against the probe server log; the per call rows are under `rows` |
| `transcript.md` | every prompt and every full reply |

## How it was produced

Run on 2026-08-14 through the Claude Code CLI with built in tools disabled and only the probe tool allowed. 2 models, 5 tool modes, 2 framings, 5 trials. What the tool returned on each call is taken from the server's own log. Verdicts are computed by deterministic code (`classify.ts` in the repository); no model judges another model. Paths in prompts point to a temporary sandbox directory. The scripts that turn these files into every number are in the GitHub repository.

## Licence

MIT, the licence of the repository, covering code and data.

## Citation

```bibtex
@misc{semenkevich2026toolfailure,
  author = {Semenkevich, Dmitriy},
  title  = {tool-failure: does the answer say the tool broke?},
  year   = {2026},
  doi    = {10.5281/zenodo.22128837},
  url    = {https://doi.org/10.5281/zenodo.22128837}
}
```