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 jeremylongshore/plugins-nixtla --skill skills-expertgit clone --depth 1 https://github.com/jeremylongshore/plugins-nixtlaWrote 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/jeremylongshore/plugins-nixtla/skills-expert)<a href="https://agentmods.dev/skills/jeremylongshore/plugins-nixtla/skills-expert"><img src="https://agentmods.dev/badge/skills/jeremylongshore/plugins-nixtla/skills-expert/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/jeremylongshore/plugins-nixtla/skills-expert"><img src="https://agentmods.dev/badge/skills/jeremylongshore/plugins-nixtla/skills-expert.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 | $0.00059 | $0.01047 |
| Opus 5 | $0.00030 | $0.00524 |
| Sonnet 5 | $0.00012 | $0.00209 |
| Haiku 4.5 | $0.00006 | $0.00105 |
Grade A, and why
skills-expert 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 yesterday.
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.
The source is not reproduced here
A licence we could not identify
The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- yesterday Changed · -155 lines · +12 tokens per session a6f530721e61
- 11d ago First seen · 268 lines · 47 tokens per session scan A 0e944a0d36e5
skills-expert is a skill published in the GitHub repository jeremylongshore/plugins-nixtla (11 stars, last pushed 2d ago), with no licence file. It adds 59 tokens to every session and 1,047 once invoked, about $0.0003 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.
Other skills, from other repositories
rules-eval
Evaluate Claude Code rules in .claude/rules/. Use for frontmatter, globs, and quality audits.
frontmatter-validation
Validate and fix YAML frontmatter metadata in markdown documentation files. Covers required fields, field formats, and schema compliance for SKILL.md and knowledge-copilot files. Use proactively when auditing documentation frontmatter, reviewing SKILL.md files, or fixing YAML metadata errors.
yaml-agent-format
YAML format for Claude Code agent definitions as alternative to markdown. Use when creating agents with YAML, converting markdown agents to YAML, or validating YAML agent schemas. Trigger keywords - "YAML agent", "agent YAML", "YAML format", "agent schema", "YAML definition", "convert to YAML".
skill-check
Validate Claude Code skills against the agentskills specification. Catches structural, semantic, and naming issues before users do.
smiles-validation
Strict SMILES validation, structural comparison, and modification verification. Catches invalid LLM-generated molecules.
regex-mastery
Use this skill when writing regular expressions, debugging pattern matching,optimizing regex performance, or implementing text validation. Triggers on regex, regular expressions, pattern matching, lookahead, lookbehind, named groups, capture groups, backreferences, and any task requiring text pattern matching.