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 serbyte-development/shellby-mcp --skill install-shellby-mcpgit clone --depth 1 https://github.com/serbyte-development/shellby-mcpWrote 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/serbyte-development/shellby-mcp/install-shellby-mcp)<a href="https://agentmods.dev/skills/serbyte-development/shellby-mcp/install-shellby-mcp"><img src="https://agentmods.dev/badge/skills/serbyte-development/shellby-mcp/install-shellby-mcp/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/serbyte-development/shellby-mcp/install-shellby-mcp"><img src="https://agentmods.dev/badge/skills/serbyte-development/shellby-mcp/install-shellby-mcp.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Excessive Agency · line 13 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
- medium Rogue Agent · line 15 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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 | $0.00047 | $0.02120 |
| Opus 5.5 | $0.00019 | $0.00848 |
| Sonnet 5.5 | $0.00009 | $0.00424 |
| Haiku 4.5 | $0.00005 | $0.00212 |
Grade A, and why
install-shellby-mcp scanned grade A 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -fsS http://127.0.0.1:3333/healthz How it starts
The opening of the file, as written. The whole thing — 197 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Install Shellby MCP
Install Shellby MCP collaboratively with the human.
Boundaries
- Inspect current machine and repository state before changing anything. Resume partial installs instead of blindly repeating setup.
- Never ask the user to paste an ngrok authtoken, ChatGPT credential, or other secret into chat. Have them enter secrets directly in their own Terminal or browser.
- Give the human concise instructions whenever macOS, Chrome, ChatGPT, or another GUI requires interaction.
- Do not run
npm start,npm run restart,npm run status,npm run logs,npm run stop, or a directpm2command before the human establishes the PM2 daemon from Terminal.app. A PM2 command may create the daemon under the wrong macOS permission source. - Never kill an existing PM2 daemon until you know what it manages and the human explicitly agrees to disrupt those processes.
pm2 killaffects the whole user-level PM2 daemon, not only Shellby. - Treat Computer Use permission status observed from the agent's own host process as non-authoritative for Terminal.app. macOS TCC permissions follow the responsible launching process.
1. Inspect the machine
Confirm:
- macOS on Apple Silicon or Intel;
- Node.js 22.13.0 or newer;
npmandgitare available;- ngrok is installed;
- this repository is present and writable.
If the repository is not already checked out, clone https://github.com/Serbyte-Development/shellby-mcp.git and enter it.
Install missing prerequisites when safe. Prefer the repository's documented ngrok installation command when Homebrew is available:
brew install --cask ngrok
Do not silently replace the user's Node installation strategy or package manager. If Node is missing or too old and there is no obvious existing version manager, tell the human what is required and let them choose how Node should be installed. Never chat $PATH without explicit approval.
2. Install repository dependencies
From the repository root:
npm ci
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 Changed afb92f034c3d
- 1mo ago Changed · +2 lines da7d8d6d8856
- 1mo ago First seen · 195 lines · 47 tokens per session scan A baab4f2ba515
install-shellby-mcp is a skill published in the GitHub repository serbyte-development/shellby-mcp (14 stars, last pushed 2d ago), licensed MIT. It adds 47 tokens to every session and 2,120 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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