AgentHarm
110 malicious agent tasks with synthetic tools. Measures refusal and harmful task completion, plus benign controls.
Implemented in Inspect Evals. Part of the test set is private.
- Made by
- Gray Swan AI + UK AI Security Institute
- Released
- October 2024
- Kind
- Refusing harmful requests
- Scored
- Checked automatically
- Answers
- Agent task
- Tasks
- Public, plus a private test set
- Strongest model tested
-
Muse Spark #53 on the capability index
- Last in a launch post
- March 2026, dropped before it saturated
- Last model added
- June 2026
- Scores refreshed
- November 12th, 2026
In the authors’ words
The robustness of LLMs to jailbreak attacks, where users design prompts to circumvent safety measures and misuse model capabilities, has been studied primarily for LLMs acting as simple chatbots. Meanwhile, LLM agents – which use external tools and can execute multi-stage tasks – may pose a greater risk if misused, but their robustness remains underexplored. To facilitate research on LLM agent misuse, we propose a new benchmark called AgentHarm. The benchmark includes a diverse set of 110 explicitly malicious agent tasks (440 with augmentations), covering 11 harm categories including fraud, cybercrime, and harassment. In addition to measuring whether models refuse harmful agentic requests, scoring well on AgentHarm requires jailbroken agents to maintain their capabilities following an attack to complete a multi-step task. We evaluate a range of leading LLMs, and find (1) leading LLMs are surprisingly compliant with malicious agent requests without jailbreaking, (2) simple universal jailbreak templates can be adapted to effectively jailbreak agents, and (3) these jailbreaks enable coherent and malicious multi-step agent behavior and retain model capabilities. To enable simple and reliable evaluation of attacks and defenses for LLM-based agents, we publicly release AgentHarm at https://huggingface.co/datasets/ai-safety-institute/AgentHarm.
Grok 4 Fast leads with 8.00% among models released by April 2026
Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.
Llama 3.1-8B leads with 3.10% across all independent runs
Best score per model across the official leaderboard, Epoch AI’s own runs and any board Epoch AI copied. Each bar and row names its source.
Llama 3.1-8B leads with 3.10%, claims included
Best score per model from every source, including labs’ own numbers and claims Epoch AI collected from reports and papers. Labs pick their own settings, so a claim can beat an independent run of the same model.
The newest model with a score here came out in April 2026, and nobody has reported a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:
- Claude Fable 5.2
-
Gemini 4 Carbon
- GPT-6 Astra
- Claude Opus 5.5
- and 16 more
- 1 Grok 4 Fast 8.00%
- 2 Grok 4 14%
- 3 Grok 4.1 14%
- 4 grok-code-fast-1 17%
- 5
Muse Spark 26%
- 6 Grok 4.20 30%
Source: Labs’ model cards
- 1
Llama 3.1-8B None attack; Standard prompt 3.10%
- 2
Llama 3.1-405B None attack; Standard prompt 4.30%
- 3 Claude 3 Haiku Template attack; Standard prompt 6.60%
- 4
Gemini 1.0 Pro None attack; Standard prompt 7.40%
- 5
Llama 3.1-70B None attack; Standard prompt 14%
- 6 Claude 3 Opus None attack; Standard prompt 14.4%
- 7 Claude 3 Sonnet None attack; Standard prompt 20.7%
- 8
Mistral Large 2 Jul 2024, None attack; Refusal prompt 69.1%
Source: Official AgentHarm leaderboard
- 1
Llama 3.1-8B None attack; Standard prompt 3.10%
- 2
Llama 3.1-405B None attack; Standard prompt 4.30%
- 3 Claude 3 Haiku Template attack; Standard prompt 6.60%
- 4
Gemini 1.0 Pro None attack; Standard prompt 7.40%
- 5 Grok 4 Fast 8.00%
- 6
Llama 3.1-70B None attack; Standard prompt 14%
- 7 Grok 4 14%
- 8 Grok 4.1 14%
- 9 Claude 3 Opus None attack; Standard prompt 14.4%
- 10 grok-code-fast-1 17%
- 11 Claude 3 Sonnet None attack; Standard prompt 20.7%
- 12
Muse Spark 26%
- 13 Grok 4.20 30%
- 14
Mistral Large 2 Jul 2024, None attack; Refusal prompt 69.1%
Sources: Official AgentHarm leaderboard and labs’ model cards
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | Grok 4 Fast | 8.00% | Sep 2025 | Lab model card | |
| 2 | Grok 4 | 14% | Aug 2025 | Lab model card | |
| 3 | Grok 4.1 | 14% | Nov 2025 | Lab model card | |
| 4 | grok-code-fast-1 | 17% | Aug 2025 | Lab model card | |
| 5 | | 26% | Jun 2026 | Lab model card | |
| 6 | Grok 4.20 | 30% | Mar 2026 | Lab model card |
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | | 3.10% | None attack; Standard prompt | Jul 2024 | Official leaderboard |
| 2 | | 4.30% | None attack; Standard prompt | Jul 2024 | Official leaderboard |
| 3 | Claude 3 Haiku | 6.60% | Template attack; Standard prompt | Mar 2024 | Official leaderboard |
| 4 | | 7.40% | None attack; Standard prompt | Dec 2023 | Official leaderboard |
| 5 | | 14% | None attack; Standard prompt | Jul 2024 | Official leaderboard |
| 6 | Claude 3 Opus | 14.4% | None attack; Standard prompt | Feb 2024 | Official leaderboard |
| 7 | Claude 3 Sonnet | 20.7% | None attack; Standard prompt | Feb 2024 | Official leaderboard |
| 8 | | 69.1% | None attack; Refusal prompt | Jul 2024 | Official leaderboard |
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | | 3.10% | None attack; Standard prompt | Jul 2024 | Official leaderboard |
| 2 | | 4.30% | None attack; Standard prompt | Jul 2024 | Official leaderboard |
| 3 | Claude 3 Haiku | 6.60% | Template attack; Standard prompt | Mar 2024 | Official leaderboard |
| 4 | | 7.40% | None attack; Standard prompt | Dec 2023 | Official leaderboard |
| 5 | Grok 4 Fast | 8.00% | Sep 2025 | Lab model card | |
| 6 | | 14% | None attack; Standard prompt | Jul 2024 | Official leaderboard |
| 7 | Grok 4 | 14% | Aug 2025 | Lab model card | |
| 8 | Grok 4.1 | 14% | Nov 2025 | Lab model card | |
| 9 | Claude 3 Opus | 14.4% | None attack; Standard prompt | Feb 2024 | Official leaderboard |
| 10 | grok-code-fast-1 | 17% | Aug 2025 | Lab model card | |
| 11 | Claude 3 Sonnet | 20.7% | None attack; Standard prompt | Feb 2024 | Official leaderboard |
| 12 | | 26% | Jun 2026 | Lab model card | |
| 13 | Grok 4.20 | 30% | Mar 2026 | Lab model card | |
| 14 | | 69.1% | None attack; Refusal prompt | Jul 2024 | Official leaderboard |
The benchmark's own leaderboard has 15 entries, 8 of them models we track. Switch the scores above to rank them together.
Scores at each effort level
Models the leaderboard ran at two or more effort levels. We don’t have enough cost data here to say what the extra effort costs.
Source: Official AgentHarm leaderboard
| Model | Effort | Harness | Score | Cost per task | Output tokens |
|---|---|---|---|---|---|
| | None attack; Standard prompt | 82.2% | |||
| | Template attack; CoT prompt | 81.6% | |||
| | None attack; CoT prompt | 81.4% | |||
| | Forced tool call attack; Standard prompt | 80.9% | |||
| | Template attack; ReAct prompt | 80.8% | |||
| | Template attack; Standard prompt | 80.5% | |||
| | Template attack; Refusal prompt | 79.5% | |||
| | None attack; ReAct prompt | 72.3% | |||
| | None attack; Refusal prompt | 69.1% | |||
| Claude 3 Sonnet | Template attack; Standard prompt | 52.8% | |||
| Claude 3 Opus | Template attack; Standard prompt | 45.7% | |||
| Claude 3 Sonnet | Forced tool call attack; Standard prompt | 42.8% | |||
| Claude 3 Haiku | Forced tool call attack; Standard prompt | 33.9% | |||
| Claude 3 Opus | Forced tool call attack; Standard prompt | 29.5% | |||
| | Template attack; Standard prompt | 27.5% | |||
| | Template attack; Standard prompt | 23.3% | |||
| Claude 3 Sonnet | None attack; Standard prompt | 20.7% | |||
| | Template attack; Standard prompt | 15% | |||
| Claude 3 Opus | None attack; Standard prompt | 14.4% | |||
| | None attack; Standard prompt | 14% | |||
| Claude 3 Haiku | None attack; Standard prompt | 11.1% | |||
| | None attack; Standard prompt | 7.40% | |||
| Claude 3 Haiku | Template attack; Standard prompt | 6.60% | |||
| | None attack; Standard prompt | 4.30% | |||
| | Template attack; Standard prompt | 4.30% | |||
| | None attack; Standard prompt | 3.10% |
2 models have held number one in labs’ own numbers since its release in October 2024 Number one over time Number one over time
Lab claims count from the day the card came out, independent runs from the model’s release. We draw one row each for the benchmark’s own leaderboard and what labs claim in their cards.
Sources: Official AgentHarm leaderboard and labs’ model cards
Scores over time
All the scores we have, one dot each, so a model tested at several settings appears more than once.
Sources: Official AgentHarm leaderboard and labs’ model cards
Labs headline it less often now, last in March 2026
Launch posts from every lab that has listed it, one tick per post. Tall colored ticks include it, and short gray ones leave it out.
| Date | Launch post | Score | As the post writes it |
|---|---|---|---|
| Mar 9, 2026 | Grok 4.20 | 30 | AgentHarm, violation rate 0.30, no jailbreak, Grok 4.2 SA, Table 1 |
7 system cards report it, from 3 labs
Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.
| Date | Document | Score | As the document writes it | Section |
|---|---|---|---|---|
| Jun 12, 2026 | | 26 | AgentHarm score (Table 2, Figure 32). Benign subset FRR 6.8 | Robustness |
| Apr 7, 2026 | Grok 4.20 model card | 30 | AgentHarm, violation rate 0.30, no jailbreak, Grok 4.2 SA, Table 1 | Safety |
| Nov 24, 2025 | | AgentHarm-Chat, harmful tasks safely refused (Table 14) | Safety | |
| Nov 17, 2025 | Grok 4.1 model card | 14 | AgentHarm, answer rate 0.14, no jailbreak, Grok 4.1 Thinking (Table 1) | Safety |
| Sep 19, 2025 | Grok 4 Fast model card | 8 | AgentHarm, answer rate 0.08, no attack, 0.10 non-reasoning (Table 1) | Safety |
| Aug 26, 2025 | grok-code-fast-1 model card | 17 | AgentHarm, answer rate 17.0 (Table 1) | Safety |
| Aug 20, 2025 | Grok 4 model card | 14 | AgentHarm, answer rate 0.14, no attack, Grok 4 API (Table 1) | Safety |
More in Safety and alignment
- FORTRESS In use Paired adversarial and benign national-security misuse prompts. Rubric-graded risk score on adversarial and over-refusal score on benign prompts. Claude Opus 5.5 5.78%
- StrongREJECT In use Forbidden-prompt jailbreak benchmark with a rubric grader that scores how useful a non-refusal actually is.
Inkling 98.6%
- Gray Swan IPI Arena benchmark In use Indirect prompt-injection attacks from public red-teaming competitions replayed on tool, coding and browser agents. Attack success rate at k attempts.
Gemini 4 Carbon 0%
- DistressBench In use Models reply as a chatbot to 718 simulated users in psychological crisis, in single-turn and multi-turn chats. Three judge models score replies against clinician-written rubrics.
Muse Spark 1.2 88.4%
- Lakera B3 (Backbone Breaker Benchmark) In use Crowdsourced prompt-injection attacks hit backbone LLMs inside agent threat snapshots at three defense levels. The score is attack resistance, 100 minus the board's vulnerability percentage. Claude Opus 4.5 89%
- IHEval In use Models face conflicts between system, user and tool instructions. Reports a composite score for following the higher-priority instruction. GPT-4o 70%