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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
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.
| 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
versionsegment reflects the version of the scanning engine (yotta-verify), not the MCP package (0.1.4). Passversionto 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 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;--listshows 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.