Borrowing it
Nothing to install: this file belongs to NazarKalytiuk/tarn. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/NazarKalytiuk/tarn/main/.cursorrulesgit clone --depth 1 https://github.com/NazarKalytiuk/tarnWrote 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/rules/nazarkalytiuk/tarn/cursorrules)<a href="https://agentmods.dev/rules/nazarkalytiuk/tarn/cursorrules"><img src="https://agentmods.dev/badge/rules/nazarkalytiuk/tarn/cursorrules/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/rules/nazarkalytiuk/tarn/cursorrules"><img src="https://agentmods.dev/badge/rules/nazarkalytiuk/tarn/cursorrules.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 | $0.00457 | $0.00457 |
| Opus 5.5 | $0.00183 | $0.00183 |
| Sonnet 5.5 | $0.00091 | $0.00091 |
| Haiku 4.5 | $0.00046 | $0.00046 |
Grade A, and why
cursorrules scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
This project uses Tarn, a CLI API testing tool. Tests are .tarn.yaml files.
When writing API tests, use the .tarn.yaml format:
name: Test name
steps:
- name: Step name
request:
method: GET|POST|PUT|PATCH|DELETE
url: "{{ env.base_url }}/path"
headers:
Content-Type: "application/json"
body:
key: "value"
capture:
var_name: "$.jsonpath"
assert:
status: 200
body:
"$.field": "expected"
"$.field": { type: string, contains: "sub", not_empty: true }
Run tests: tarn run, tarn run --format json
Validate: tarn validate
List: tarn list
Assertion operators: eq, not_eq, type, contains, not_contains, starts_with, ends_with, matches, not_empty, exists, length, gt, gte, lt, lte. Built-ins: {{ $uuid }} (alias for {{ $uuid_v4 }}), {{ $uuid_v4 }}, {{ $uuid_v7 }}, {{ $timestamp }}, {{ $now_iso }}, {{ $random_hex(n) }}, {{ $random_int(min, max) }}. Faker built-ins (EN, seedable via TARN_FAKER_SEED or tarn.config.yaml faker.seed): {{ $email }}, {{ $first_name }}, {{ $last_name }}, {{ $name }}, {{ $username }}, {{ $phone }}, {{ $word }}, {{ $words(n) }}, {{ $sentence }}, {{ $slug }}, {{ $alpha(n) }}, {{ $alnum(n) }}, {{ $choice(a, b, ...) }}, {{ $bool }}, {{ $ipv4 }}, {{ $ipv6 }}. Format assertions: is_uuid (any version), is_uuid_v4, is_uuid_v7, is_date, is_ipv4, is_ipv6. Env resolution: --var > shell env > tarn.env.local.yaml > tarn.env.{name}.yaml > tarn.env.yaml > inline env:.
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 · 34 lines · 457 tokens per session scan A 13c430f048ec
cursorrules is a cursor rule published in the GitHub repository NazarKalytiuk/tarn (5 stars, last pushed 4mo ago), licensed MIT. It adds 457 tokens to every session, about $0.0018 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 2026-08-31.
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