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 instructions/nazarkalytiuk/tarn/agents-mdgit 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/instructions/nazarkalytiuk/tarn/agents-md)<a href="https://agentmods.dev/instructions/nazarkalytiuk/tarn/agents-md"><img src="https://agentmods.dev/badge/instructions/nazarkalytiuk/tarn/agents-md.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 | $0.02678 | $0.02678 |
| Opus 5 | $0.01339 | $0.01339 |
| Sonnet 5 | $0.00536 | $0.00536 |
| Haiku 4.5 | $0.00268 | $0.00268 |
Grade C, and why
tarn AGENTS.md scanned grade C with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Harvests environment variableshighData exfiltration
Enumerating or grepping the environment for keys collects credentials unrelated to what the mod says it does.
- Code actions: **extract env var**, **capture this field**, **scaffold assert from recorded response**. How it starts
The opening of the file, as written. The whole thing — 247 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Tarn — AI Agent Integration Guide
Tarn is a CLI API testing tool. Tests are YAML files (.tarn.yaml), results are structured JSON.
Quick Reference
tarn run # run all tests in tests/
tarn run tests/users.tarn.yaml # run specific file
tarn run --format json # structured JSON output (for parsing)
tarn validate # check syntax without running
tarn list # list all tests
Writing a Test
name: User API
steps:
- name: Create user
request:
method: POST
url: "{{ env.base_url }}/users"
headers:
Content-Type: "application/json"
body:
name: "Jane Doe"
email: "[email protected]"
capture:
user_id: "$.id" # JSONPath (type-preserving)
# session: # header capture with regex
# header: "set-cookie"
# regex: "session=([^;]+)"
assert:
status: 201 # also: "2xx", { in: [200,201] }, { gte: 200, lt: 300 }
body:
"$.name": "Jane Doe"
"$.id": { type: string, not_empty: true }
- name: Get user
request:
method: GET
url: "{{ env.base_url }}/users/{{ capture.user_id }}"
assert:
status: 200
body:
"$.name": "Jane Doe"
Assertion Operators
| Operator | Example | Description |
|---|---|---|
| (literal) | "$.name": "Alice" |
Exact match |
eq |
{ eq: "Alice" } |
Explicit equality |
not_eq |
{ not_eq: "Bob" } |
Not equal |
type |
{ type: string } |
Type check (string/number/boolean/array/object/null) |
contains |
{ contains: "sub" } |
Substring or array element |
not_contains |
{ not_contains: "x" } |
Inverse of contains |
starts_with |
{ starts_with: "usr_" } |
String prefix |
ends_with |
{ ends_with: ".com" } |
String suffix |
matches |
{ matches: "^[a-z]+$" } |
Regex match |
not_empty |
{ not_empty: true } |
Non-empty string/array/object |
exists |
{ exists: true } |
Field exists |
length |
{ length: 5 } |
Exact length |
gt/gte/lt/lte |
{ gt: 0 } |
Numeric comparison |
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 · 247 lines · 2,678 tokens per session scan C 8cb0c748626f
tarn AGENTS.md is an instructions file published in the GitHub repository NazarKalytiuk/tarn (5 stars, last pushed 3mo ago), licensed MIT. It adds 2,678 tokens to every session, about $0.0134 per session on Opus 5. A static security scan graded it C with 1 finding (harvests environment variables). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
Other instructions, from other repositories
Math-To-Manim tests.instructions.md
Guidelines for writing and maintaining tests in Math-To-Manim.
antigravity-testing-kit GEMINI.md
Instructions for anhtester/antigravity-testing-kit, covering gemini ai - global automation agent rules, git pull restriction rule, browser rules (mandatory), 🖥️ viewport & mode and 🔄 thứ tự debug bắt buộc (playwright mcp).
android-qa-kit AGENTS.md
Instructions for willbytee-sudo/android-qa-kit, covering agents.md — setting up and driving an android device, 1. how to work with the user, 2. start by finding out what's already there, 3. what you can do in each mode and 4. if there's no device: ask first.
devicecloud-mcp AGENTS.md
AGENTS.md instructions for RubenGlez/devicecloud-mcp, covering devicecloud-mcp, who it's for, the problem, the promise and why it's different.
refract AGENTS.md
AGENTS.md instructions for valternunez/refract, covering refract — agent playbooks, playbook: verify a responsive bug fix, playbook: visual-diff before merge, playbook: screenshot a page behind a login and playbook: find horizontal overflow on a pr preview.
mcp-server-tester CLAUDE.md
Claude Code instructions for gleanwork/mcp-server-tester, a project described as: Playwright-based testing and eval framework for MCP servers with LLM-as-a-judge.