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/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/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/instructions/nazarkalytiuk/tarn/agents-md"><img src="https://agentmods.dev/badge/instructions/nazarkalytiuk/tarn/agents-md.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 | $0.02678 | $0.02678 |
| Opus 5.5 | $0.01071 | $0.01071 |
| Sonnet 5.5 | $0.00536 | $0.00536 |
| Haiku 4.5 | $0.00268 | $0.00268 |
Grade C, and why
tarn AGENTS.md scanned grade C with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Harvests environment variableshighData exfiltration
Enumerating or grepping the environment for keys collects credentials unrelated to what the mod says it does.
- Code actions: **extract env var**, **capture this field**, **scaffold assert from recorded response**. How it starts
The opening of the file, as written. The whole thing — 247 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Tarn — AI Agent Integration Guide
Tarn is a CLI API testing tool. Tests are YAML files (.tarn.yaml), results are structured JSON.
Quick Reference
tarn run # run all tests in tests/
tarn run tests/users.tarn.yaml # run specific file
tarn run --format json # structured JSON output (for parsing)
tarn validate # check syntax without running
tarn list # list all tests
Writing a Test
name: User API
steps:
- name: Create user
request:
method: POST
url: "{{ env.base_url }}/users"
headers:
Content-Type: "application/json"
body:
name: "Jane Doe"
email: "[email protected]"
capture:
user_id: "$.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.
- 2mo 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 4mo ago), licensed MIT. It adds 2,678 tokens to every session, about $0.0107 per session on Opus 5.5. 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
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.