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Lazaretto MCP

by jamesdfinance-dev

Checks pinned dependencies and artifacts for malicious-package indicators and deterministic behavioral risks.

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Install Lazaretto MCP

Pick your client, then add it in one click or paste the config.

STDIONode.js
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "jamesdfinance-dev-lazaretto-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "lazaretto-mcp"
      ],
      "env": {
        "LAZARETTO_API_KEY": "YOUR_VALUE_HERE",
        "LAZARETTO_BASE_URL": "YOUR_VALUE_HERE"
      }
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Values are written into the snippet above so you can paste it as is. They never leave your browser.

Automated check passed— started and listed 8 tools correctly (1mo ago).

Overview

The jamesdfinance-dev/lazaretto-mcp MCP server checks lockfiles, package artifacts, and MCP tool descriptions against Lazaretto's security analysis service. It can run as a hosted Streamable HTTP server or locally over stdio, with free checks requiring no API key and deeper scans using prepaid credits. Lockfile checks cover npm, Yarn, and pnpm formats, while artifact scans return verdicts with file, line, and evidence details. Reach for it before installing dependencies, agent skills, or MCP tools.

Use cases

  • Check pinned dependencies before installing them
  • Scan packages or repositories for suspicious behavior
  • Verify a previously issued Lazaretto attestation
  • Inspect MCP tools for prompt injection or tool poisoning

Key features

  • Lockfile checks for npm, Yarn, and pnpm
  • Known-bad SHA-256 hash lookup
  • Deterministic artifact behavioral analysis
  • MCP tool and endpoint inspection
  • Signed scan attestation verification
  • Free checks without an API key

Tools8

What Lazaretto MCP lets your agent do. Expand a tool for its parameters.

Verified live~4.6k tokens of context

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked Today

Recent health check succeeded.

8/8 checks healthy over the last 91d

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 3d ago via OSV.dev · lazaretto-mcp (npm)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

GitHub stars1Stargazers on the source repository.
npm downloads1.6kPackage downloads in the last 30 days.
Last commit3d agoMost recent push to the default branch.
Availability100%Our rolling endpoint + install checks that succeeded.
Install checkPassedOur sandbox started it and listed its tools.
Tools exposed8Callable tools this server registers over MCP.
Directory activity3 viewsConfig copies, upvotes, and views on AllMCPs.

How Lazaretto MCP works

What jamesdfinance-dev/lazaretto-mcp MCP server does

The jamesdfinance-dev/lazaretto-mcp MCP server provides pre-install verification for software packages, AI agent skills, and MCP tools. Its free lockfile workflow examines exactly pinned dependencies and compares them with published malicious-package advisories from OSV and OpenSSF. It can also check whether a SHA-256 artifact hash appears in Lazaretto's known-bad indicator store.

The resulting verdict can be malicious, flagged, clear, or error, with evidence tied to the finding. MCP-specific checks analyze tool names, descriptions, schemas, and instructions for patterns such as tool poisoning or attempts to move secrets and conversation data.

How it works

The jamesdfinance-dev/lazaretto-mcp MCP server is a thin client for the Lazaretto API. It makes HTTPS requests and does not include the detection engine itself. Lockfile checks read files from the agent's working directory, so the complete dependency file does not need to be pasted into the model context. Supported inputs include package-lock.json, npm-shrinkwrap.json, yarn.lock, and pnpm-lock.yaml.

A lockfile result is only an all-clear when both the malicious and unverified collections are empty. Artifact results include the file, line, and evidence associated with a rule match. Scan verdicts are bound to a SHA-256 subject, and signed attestations can be checked later without rescanning or paying again. A previously clear subject may be marked contradicted if it becomes known-bad.

Setup and configuration

Use the hosted endpoint at https://lazaretto.dev/mcp with an MCP client that supports remote Streamable HTTP servers. The optional X-API-Key header identifies prepaid credits for paid operations. check_lockfile, known_bad_lookup, and verify_attestation do not require a key. Artifact and MCP scans require credits, which can be purchased as a bundle or topped up through the documented x402 endpoint.

For local stdio use, clone the repository, run npm install, and start node index.mjs with LAZARETTO_API_KEY when paid operations are needed. LAZARETTO_BASE_URL can replace the default https://lazaretto.dev API host. The package also documents npx lazaretto-mcp as a one-line launch command.

Tools and capabilities

  • check_lockfile: checks pinned dependencies against malicious-package advisories.
  • known_bad_lookup: matches a SHA-256 content hash against a daily-refreshed indicator store.
  • verify_attestation: validates Lazaretto's signed scan attestation and returns its claims.
  • scan_artifact: analyzes fetched or inline targets without running them.
  • check_mcp_tools: analyzes pasted MCP tool-list JSON without contacting the server.
  • scan_mcp_server: calls only initialize and tools/list on an MCP endpoint before analyzing its exposed text.

Limitations and notes

The jamesdfinance-dev/lazaretto-mcp MCP server reports signals and evidence rather than providing a security warranty. A clear result means no known-bad match or rule fired; it is not a general statement that the target is safe. For attestation verification, the artifact you plan to run must still match claims.sub. External MCP servers that run only over stdio cannot be reached by scan_mcp_server; their tool-list JSON can instead be submitted to check_mcp_tools. The MCP package is MIT licensed, while the Lazaretto service and detection engine are separate proprietary components.

Read the full README View source on GitHub

Reviews

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Frequently Asked Questions about Lazaretto MCP

Run `npx -y lazaretto-mcp`, or clone the repository, run `npm install`, and start `node index.mjs` for local stdio use.

Free lockfile checks, known-bad lookups, and attestation verification do not require an API key. Artifact and MCP scans require prepaid credits and an API key.

Configure the client with the hosted Streamable HTTP URL `https://lazaretto.dev/mcp` and optionally provide the `X-API-Key` header.

It supports `package-lock.json`, `npm-shrinkwrap.json`, `yarn.lock`, and `pnpm-lock.yaml`.

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