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 gtwatts/mainframe --skill opencodegit clone --depth 1 https://github.com/gtwatts/mainframeWrote 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/gtwatts/mainframe/opencode)<a href="https://agentmods.dev/skills/gtwatts/mainframe/opencode"><img src="https://agentmods.dev/badge/skills/gtwatts/mainframe/opencode/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/gtwatts/mainframe/opencode"><img src="https://agentmods.dev/badge/skills/gtwatts/mainframe/opencode.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 | $0.00022 | $0.03080 |
| Opus 5.5 | $0.00009 | $0.01232 |
| Sonnet 5.5 | $0.00004 | $0.00616 |
| Haiku 4.5 | $0.00002 | $0.00308 |
Grade C, and why
mainframe 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 1mo 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.
Hidden instructionshighPrompt injection
Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.
<!-- MAINFRAME-HOST-CONTRACT {"schema_version":1,"contract_version":"1.3.0","registry":"config/host-capabilities.json","registry_sha256":"0b4a8b98161b5caddf7a2ebdfd26d1c2b8f0a8967fbbf89818cdf2ed4b1e3fc5","host":"opencode This is a copy
94% identical to mainframe — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Instruction evidence: instructions only. Runtime configuration, enforcement, live use, and release status are platform-bound in config/host-capabilities.json; unsupported routes remain unverified.
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.
- 1mo ago First seen · 87 lines · 22 tokens per session scan C f06ef45ab1c3
mainframe is a skill published in the GitHub repository gtwatts/mainframe (12 stars, last pushed 5d ago), licensed MIT. It adds 22 tokens to every session and 3,080 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it C with 1 finding (hidden instructions). It is 94% identical to mainframe, differing in 2 lines, and is treated as a copy.
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