A JavaScript and TypeScript tool for running unit tests, which check small pieces of code separately. It works with Vite, a tool commonly used to build modern web applications, and provides an API similar to Jest.

Use it when writing unit tests, creating mocks, setting up coverage, filtering tests, or working with test fixtures.

It gives developers a way to check code, replace outside dependencies with test doubles, measure coverage, and run selected tests.

How jeius/mcp-servers configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to jeius/mcp-servers. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/jeius/mcp-servers/main/.agents/skills/vitest/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/jeius/mcp-servers

Made for: Claude Code, Codex.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/jeius/mcp-servers/vitest/github.svg)](https://agentmods.dev/skills/jeius/mcp-servers/vitest)

Your own site

<a href="https://agentmods.dev/skills/jeius/mcp-servers/vitest"><img src="https://agentmods.dev/badge/skills/jeius/mcp-servers/vitest/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/jeius/mcp-servers/vitest"><img src="https://agentmods.dev/badge/skills/jeius/mcp-servers/vitest.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 832 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin unknown No closer match found in the catalogue.

Token cost

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	$0.00036	$0.00832
Opus 5.5	$0.00014	$0.00333
Sonnet 5.5	$0.00007	$0.00166
Haiku 4.5	$0.00004	$0.00083

Measured 2mo ago against content hash 2da9b15c28b9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

vitest 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 2mo 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.

.agents/skills/vitest/SKILL.md · 56 lines

The source is not reproduced here

No licence file

Read it on GitHub

Files

What ships with it

20 files 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.

Changes

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.

2mo ago First seen · 56 lines · 36 tokens per session scan A 2da9b15c28b9

Subscribe to this mod's changes

vitest is a skill published in the GitHub repository jeius/mcp-servers (0 stars, last pushed 2mo ago), with no licence file. It adds 36 tokens to every session and 832 once invoked, about $0.0001 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 2026-08-31.

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mcp-servers: Skill for Claude Code