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 agentmods add skills/strategic-automation/violin/api-testingnpx skills add Strategic-Automation/violin --skill api-testinggit clone --depth 1 https://github.com/Strategic-Automation/violinWrote 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/strategic-automation/violin/api-testing)<a href="https://agentmods.dev/skills/strategic-automation/violin/api-testing"><img src="https://agentmods.dev/badge/skills/strategic-automation/violin/api-testing.svg" alt="Measured on agentmods" 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 | $0.00017 | $0.00393 |
| Opus 5 | $0.00009 | $0.00197 |
| Sonnet 5 | $0.00003 | $0.00079 |
| Haiku 4.5 | $0.00002 | $0.00039 |
Grade A, and why
api-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 4d 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.
What it actually says
API Security Testing
On-demand skill for API protocol, inventory, schema, and machine-to-machine attack surfaces. It covers REST, GraphQL, SOAP, and WebSocket endpoints; load the targeted playbook rather than treating APIs as ordinary web routes. Model Context Protocol (MCP) surfaces route to llm-security.
When to Use
- OpenAPI/Swagger, GraphQL, SOAP, or WebSocket endpoints are discovered or in scope.
- The assessment needs endpoint inventory, version/legacy discovery, protocol-specific authorization checks, or schema-driven testing.
- Do not use this as a substitute for a dedicated root-cause playbook (for example IDOR, JWT, SSRF, or SQLi); route and load that playbook after API discovery identifies the class.
Playbook Routing
| Surface | Playbook |
|---|---|
| REST / SOAP / GraphQL / WebSocket API security | playbooks/api-security.md |
Common Pitfalls
- Inventory versions, undocumented endpoints, methods, schemas, and authentication contexts before fuzzing.
- Preserve full request/response pairs and protocol headers, including negotiated sessions.
- Keep rate, depth, batching, and streaming probes within the approved RoE.
Verification Checklist
- Engagement bootstrap and scope validation succeeded.
- The API surface inventory identifies protocol, version, authentication, and schema sources.
- The root-cause playbook was loaded for every confirmed vulnerability class.
What ships with it
1 file 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.
- 4d ago First seen · 41 lines · 17 tokens per session scan A 214c6c790b6c
api-testing is a skill published in the GitHub repository Strategic-Automation/violin (85 stars, last pushed today), licensed MIT. It adds 17 tokens to every session and 393 once invoked, about $0.0001 per session on Opus 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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