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 skills/serbyte-development/shellby-mcp/create-skillnpx skills add serbyte-development/shellby-mcp --skill create-skillgit clone --depth 1 https://github.com/serbyte-development/shellby-mcpWhat 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 | $0.00046 | $0.00588 |
| Opus 5 | $0.00023 | $0.00294 |
| Sonnet 5 | $0.00009 | $0.00118 |
| Haiku 4.5 | $0.00005 | $0.00059 |
Grade A, and why
create-skill 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 2d 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.
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.
How it starts
The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Create Skill
Create small reusable workflows that Shellby MCP can discover from the configured workspace.
Workspace
- Treat the configured Shellby workspace as
<workspace>. Determine it from the MCP instructions or current shell context. Never assume a username or absolute path. - Store MCP skills at
<workspace>/skills/<name>/SKILL.md. - Read
<workspace>/AGENTS.mdand inspect existing skills before changing the catalog. - Use lowercase hyphenated skill names. Keep the directory name and frontmatter
nameidentical.
Skill structure
Minimum:
skills/<name>/
└── SKILL.md
Optional resources when they materially improve repeated use:
skills/<name>/
├── SKILL.md
├── scripts/
├── references/
└── assets/
scripts/: deterministic or repeatedly reused operations.references/: detailed material loaded only when needed.assets/: templates or files consumed by the workflow.
Keep the important workflow in SKILL.md. Avoid extra documentation unless the skill needs it as working material.
Frontmatter
Use:
---
name: example-skill
description: What the skill does and concrete requests that should trigger it.
---
skill_list exposes the directory name and frontmatter description, so make the description specific enough for an agent to know when to load it.
Workflow
- Inspect existing skills for overlap and conventions.
- Define the requests that should trigger the skill.
- Capture only reusable instructions, constraints, domain knowledge, scripts, references, and assets needed for those requests.
- Create or update
<workspace>/skills/<name>/SKILL.md. - Use
skill_listto verify discovery. - Use
skill_loadto verify the complete instructions load correctly. - Exercise complex skills on a realistic request when useful.
Portability
- Prefer paths relative to
<workspace>or the skill directory. - Do not assume Codex, Claude, a particular username, or another agent runtime is installed.
- If the user explicitly wants one skill shared with another runtime, inspect that runtime's supported skill location and symlink or share a canonical directory only when both runtimes can consume the same files correctly.
- Avoid runtime-specific tool names unless the skill is intentionally specific to that runtime.
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.
- 2d ago First seen · 82 lines · 46 tokens per session scan A 2ff901832a67
create-skill is a skill published in the GitHub repository serbyte-development/shellby-mcp (10 stars, last pushed 4d ago), licensed MIT. It adds 46 tokens to every session and 588 once invoked, about $0.0002 per session on Opus 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 2026-08-31.
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