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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

MCP tools

MCP client configuration

You usually do not need to write the mcpServers entry yourself: after installing this skill, an AI agent auto-adds the yotta-verify-mcp entry per the「AI 自动接入」section in SKILL.md, and falls back to the CLI scanner when MCP tools are unavailable.

Tool reference

scan_skill

Scan a skill directory or package before install.

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).

Note: the badge's version segment reflects the version of the scanning engine (yotta-verify), not the MCP package (0.1.4). Pass version to override.

gate_check

CI pre-install gate.

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

get_report

Generate a verification report.

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 learn how to configure and use the MCP server. 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

The package ships its own test suite (included in the published package):

# Run the full suite (32 cases) from the skill directory (Python 3.8 / 3.13 both green)
python scripts/test_yotta_verify_mcp.py

# 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.