Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add mnvsk97/agentbreak --skill agent-resilience-testinggit clone --depth 1 https://github.com/mnvsk97/agentbreakWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/mnvsk97/agentbreak/agent-resilience-testing)<a href="https://agentmods.dev/skills/mnvsk97/agentbreak/agent-resilience-testing"><img src="https://agentmods.dev/badge/skills/mnvsk97/agentbreak/agent-resilience-testing/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/mnvsk97/agentbreak/agent-resilience-testing"><img src="https://agentmods.dev/badge/skills/mnvsk97/agentbreak/agent-resilience-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00097 | $0.01089 |
| Opus 5.5 | $0.00039 | $0.00436 |
| Sonnet 5.5 | $0.00019 | $0.00218 |
| Haiku 4.5 | $0.00010 | $0.00109 |
Grade A, and why
agent-resilience-testing scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Agent Resilience Testing
This skill is the orchestrator. AgentBreak is the deterministic engine for live fault injection; static checks and guardrail probes fill the gaps that a proxy cannot observe directly.
Core Rules
- Run the real
agentbreakCLI for initialization, validation, inspection, proxying, scorecards, and history. - Cover all four lanes: LLM failure modes, agent skill supply chain, guardrails, and MCP server/tool behavior.
- Treat mock-mode direct requests as endpoint smoke tests, not full agent resilience evidence.
- Treat proxy-mode traffic through the user's actual agent as the primary resilience signal.
- If MCP is enabled, run
agentbreak inspectbefore testing. If inspect fails, stop and ask whether to fix MCP config or disable MCP testing. - If proxy auth or connection validation fails, stop and fix that first. Do not run chaos tests against broken upstream auth.
- Always clean up local processes and restore temporary
.envchanges after a run. - Ask before changing project config files unless the user has already explicitly asked you to perform setup.
Orchestrator Workflow
-
Check AgentBreak
- Run
agentbreak --help. - If missing, detect
uvor an active virtualenv and install with the least invasive command.
- Run
-
Map The System
- Inspect the repo for provider, framework, MCP usage, agent skills/capabilities, guardrails, tool calls, base URLs, retry logic, timeout handling, and error paths.
- Read
references/detection.mdfor scan patterns and what to report. - Present concise findings and choose mock or proxy mode.
-
Build The Four-Lane Test Plan
- Read
references/coverage.md. - Lane 1: LLM failures: outages, brownouts, rate limits, context/token failures, malformed outputs, prompt injection, and streaming failures.
- Lane 2: Agent skills: scan installed/local skills for unsafe instructions, secret access, network exfiltration, downloads, dangerous commands, and hidden prompt injection.
- Lane 3: Guardrails: verify input, output, tool-argument, tool-result, PII/secrets, policy, and human-approval checks.
- Lane 4: MCP: test server failures, tool failures, bad schemas, bad results, registry drift, rug pulls, poisoning, and cross-tool attacks.
- Read
What ships with it
7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 78 lines · 97 tokens per session scan A 2921f2844597
agent-resilience-testing is a skill published in the GitHub repository mnvsk97/agentbreak (20 stars, last pushed 5mo ago), licensed MIT. It adds 97 tokens to every session and 1,089 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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