System Prompts Leaks is a collection of captured system instructions used to guide AI chatbots and coding agents before they receive user messages. It serves researchers and developers studying how different AI assistants are directed.
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 asgeirtj/system_prompts_leaks --skill web-gui-testergit clone --depth 1 https://github.com/asgeirtj/system_prompts_leaksWrote 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/asgeirtj/system_prompts_leaks/web-gui-tester)<a href="https://agentmods.dev/skills/asgeirtj/system_prompts_leaks/web-gui-tester"><img src="https://agentmods.dev/badge/skills/asgeirtj/system_prompts_leaks/web-gui-tester/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/asgeirtj/system_prompts_leaks/web-gui-tester"><img src="https://agentmods.dev/badge/skills/asgeirtj/system_prompts_leaks/web-gui-tester.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 | $0.00132 | $0.03148 |
| Opus 5.5 | $0.00053 | $0.01259 |
| Sonnet 5.5 | $0.00026 | $0.00630 |
| Haiku 4.5 | $0.00013 | $0.00315 |
Grade A, and why
web-gui-tester 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 today.
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.
Copies of this mod
1 near-identical copy found in the catalogue:
- web-gui-tester — 100% identical, 22 lines differ
How it starts
The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Core Principles
- Pure GUI black-box testing: Interact only with elements that are visible and operable on the page, simulating real user behavior. During verification, screenshots and/or read-only DOM inspection are allowed, but injecting JavaScript to modify page state, trigger interactions, or bypass frontend logic is strictly prohibited.
- Faithful to the actual page: All conclusions must be based on the page's actual behavior. Do not guess or speculate. If a normal GUI operation fails, stop and report it; do not use alternative methods to force progress.
- Separate testing from fixing: Do not modify the code under test during testing. If a bug blocks the current path, record the issue, skip that path, and continue testing other unaffected points. Only begin fixing bugs after testing is explicitly declared complete and the user has explicitly or implicitly requested code changes.
- Cross-validate code and visuals: Observations must include both read-only code verification (DOM state checks) and visual verification using screenshots. The two must corroborate each other and cannot replace one another. A test point without at least one visually inspected screenshot as evidence—an image returned directly by the tool, or a screenshot file read using the Read tool—must be considered incomplete. Do not conclude that a test point passed or failed without such evidence.
- Follow the browser tooling's own usage rules: Run the test with whatever browser automation tooling the session actually provides (a browser automation MCP tool, a built-in browser runtime, etc.). If that tooling ships its own usage skill or API documentation, complete its required initialization and read that documentation first, and obey its rules for actions, element location, waiting, and observation throughout the test. This skill defines the testing methodology only; when it conflicts with the tooling's own rules, the tooling's rules win.
Phase One: Scenario Assessment and Test Planning
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.
- today First seen · 158 lines · 0 tokens per session scan A 3606fe591ef0
web-gui-tester is a skill published in the GitHub repository asgeirtj/system_prompts_leaks (70,113 stars, last pushed today), licensed CC0-1.0. It adds 132 tokens to every session and 3,148 once invoked, about $0.0005 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 2026-10-24.
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