yotta-verify-mcp

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yotta-verify-mcp · 元信MCP (YuanXin MCP)

YottaMeta's pre-install security scanner for Agent skills, exposed as a stdio MCP server. Before you install any skill, plugin or MCP server, it runs a deterministic static scan — prompt injection, malicious patterns, SKILL.md integrity and permissions — and returns a verdict, an audited badge, a CI gate and a report as MCP tools.

Activates when configuring the 元信 MCP server in an MCP client, wiring a trust-scan into an agent / workflow, or calling the MCP tools.

Zero dependencies (Python 3.8+ standard library); Windows + Linux + macOS; fully local and offline — no network calls, no execution of the scanned code.

What it is

The skill / plugin market has a trust problem: a 2025 survey of 22,511 skills found 140,963 issues, and 36% contain prompt injection. 元信 MCP gives you a deterministic answer before you install — the same scan as the yotta-verify CLI, exposed as four MCP tools so any MCP client (Claude, VS Code, Codex, Cursor, …) can call it.

It is a pre-install verifier, not a sandbox and not a runtime monitor: it only reads files and prints a report. It never executes the scanned code, never connects to the network for the scan, and never fixes anything.

Why use it

Advantage	Description
Trust before install	A deterministic verdict for any skill / MCP server, instead of "trust me"
Zero dependency	Python 3.8+ standard library; no daemon / database / network
Fully local offline	Scans directories and npm tarballs on disk; nothing is executed or uploaded
Drop into any MCP client	Standard stdio MCP server — configure the server, and the four tools appear
Family synergy	Same rules table as yotta-verify (single source); verdicts merge with yotta-vetter / yotta-security-audit
Free & open	MIT; the whole scanner is free

MCP tools

Tool	What it does
scan_skill	Pre-install scan: target (dir / .tgz / npm package) → verdict + severity counts + findings
generate_badge	Audited badge: local SVG + shields.io URL; folds in validate / vetter / audit / version / tests
gate_check	CI gate: fail when the worst severity exceeds max_severity (default medium)
get_report	Verification report: Markdown or JSON, same format as the CLI

MCP client configuration

MCP configuration is optional. An AI agent may show you the target config file, the exact mcpServers JSON, and the effect, then wait for your explicit consent before writing anything. If you decline, use the bundled CLI scanner directly; the scan result is unchanged.

Tool reference

scan_skill

Scan a skill directory or package before install.

Param	Type	Required	Meaning
target	string	yes	Skill directory path, .tgz / .tar.gz path, or npm package name (auto npm pack to a temp dir, then scan)

Returns a JSON result: verdict, severity counts, and findings (prompt injection / malicious patterns / SKILL.md integrity).

generate_badge

Generate an audited badge (local SVG + shields.io URL).

Param	Type	Meaning
target	string	Optional: scan this to derive the verdict
verdict	string	Optional: set the verdict directly
validate	string	Optional: pass / fail (validate-skill result)
vetter / audit	string	Optional: external verdicts to fold in
version	string	Optional: version label. Defaults to the scanner (yotta-verify) version (e.g. 0.1.1)
tests	integer	Optional: engine test count
out	string	Optional: write the SVG to this path

Note: the badge's version segment reflects the version of the bundled scanning engine (yotta-verify), which may differ from the MCP package version. Pass version to override.

gate_check

CI pre-install gate.

Param	Type	Meaning
target	string	Required: dir / package to scan
max_severity	string	Optional: info / low / medium / high / critical (default medium)

Returns pass, verdict, worst, max_severity and an exit code.

get_report

Generate a verification report.

Param	Type	Meaning
target	string	Required: dir / package to scan
format	string	Optional: json / markdown (default markdown)
out	string	Optional: write the report to this path

Boundary

This is a local, offline, static scan:

• Directory scan is fully offline — content never leaves your machine.
• npm package scan only downloads the public package into a temporary directory (then removes it); it does not upload your content and does not execute the scanned package code.
• It does not perform dynamic analysis, does not fix anything, and does not make the final decision. Treat the verdict as a strong signal and confirm any "install / don't install" decision yourself.
• Only scan targets you are authorised to evaluate.

Installation of the skill

The package also ships a SKILL.md so an agent can explain how to configure and use the MCP server with explicit user consent. Pick any of the four methods below (skill files come from npm; GitHub can be slow without a proxy).

Method 1: npm one-liner (recommended)

# Optional China mirror: npm config set registry https://registry.npmmirror.com
npx -y @yottameta/yotta-verify-mcp --agent <agent-name>      # install to the agent's default user-level skills dir
npx -y @yottameta/yotta-verify-mcp --dir <your-skills-dir>   # point to the skills dir itself (e.g. ~/.codex/skills)

• --agent <name> installs to that agent's default user-level directory; --list shows each agent's default directory.
• --dir <path> installs to the given directory.
• The installer also starts an MCP server when run with no arguments: npx -y @yottameta/yotta-verify-mcp.

Method 2: git clone (developers / git available)

git clone https://github.com/YottaMeta/yotta-verify-mcp.git <your-skills-dir>/yotta-verify-mcp

Method 3: GitHub Download ZIP (manual / no git)

On the GitHub repository YottaMeta/yotta-verify-mcp, click Code → Download ZIP, unzip it and put the yotta-verify-mcp folder into the agent's skills directory.

Method 4: install.sh (multi-agent one-liner script)

bash install.sh --agent <name>   # install to the agent's default user-level directory
bash install.sh --dir <path>     # install to the given directory
bash install.sh --list           # list agents -> default directories

Development & validation

Repository validation includes the MCP engine suite and a documentation consent regression:

# MCP engine suite (Python 3.8 / 3.13)
python scripts/test_yotta_verify_mcp.py

# Documentation consent regression
node --test test/docs-consent.test.js

# Run the MCP server directly for debugging
python scripts/yotta_verify_mcp.py

References: references/trust-checklist.md (pre-install trust checklist for MCP servers / plugins).

License

MIT © YottaMeta — see LICENSE.