---
title: "The Lazaretto MCP server. Zero install"
description: "Point any MCP-capable agent at https://lazaretto.dev/mcp. Check a lockfile, look up a known-bad hash, find or verify an attestation for free, and run full behavioral scans against prepaid credits."
url: "https://lazaretto.dev/mcp"
---

[Home](https://lazaretto.dev/) / [Agents](https://lazaretto.dev/agents) / MCP server

Remote MCP server

# The Lazaretto MCP server

This URL is the server. It speaks MCP over Streamable HTTP, so the protocol traffic is a JSON-RPC `POST` to this same address. There is no server-initiated event stream and no server-side session, so a `GET` gets this page and a `DELETE` does nothing. You are reading it because you opened the endpoint rather than connected to it.

`https://lazaretto.dev/mcp`

## Connect

Add it to any MCP-capable client. Nothing to install, no local process:

```
{
  "mcpServers": {
    "lazaretto": {
      "type": "http",
      "url": "https://lazaretto.dev/mcp"
    }
  }
}
```

That is enough for every free tool below. For the metered ones, add a key:

```
{
  "mcpServers": {
    "lazaretto": {
      "type": "http",
      "url": "https://lazaretto.dev/mcp",
    "headers": { "X-API-Key": "your-key" }
    }
  }
}
```

A free developer key with 10 scans a day comes from `POST https://lazaretto.dev/v1/trial`, or from the `get_free_key` tool on this server, so an agent can get one without leaving the session. Agents holding a wallet can pay per call in USDC on Base over x402 at `POST https://lazaretto.dev/v1/scan`, with no account.

A person without a crypto wallet can buy the same packs with a card at [https://lazaretto.dev/buy](https://lazaretto.dev/buy).

[Setup steps for Claude Code, Cursor, VS Code and more](https://lazaretto.dev/agents)

## Tools

### Free, no key

| Tool | Cost | What it does |
| --- | --- | --- |
| `known_bad_lookup` | free, no key | Known-bad hash lookup |
| `check_lockfile` | free, no key | Lockfile malware check |
| `find_attestation` | free, no key | Find an existing attestation |
| `verify_attestation` | free, no key | Verify a scan attestation |
| `get_free_key` | free, no key | Get a free developer key |

### Metered, on an `X-API-Key` holding credits

| Tool | Cost | What it does |
| --- | --- | --- |
| `scan_artifact` | one credit | Full behavioral scan |
| `scan_lockfile_deep` | one credit | Deep scan a whole lockfile |
| `scan_mcp_server` | one credit | Scan an MCP server before connecting |
| `check_mcp_tools` | one credit | Check tool definitions you already have |

One credit per verdict, and per package for the lockfile scan. An `error` verdict is never billed.

## Check it from a terminal

```
curl -s -X POST https://lazaretto.dev/mcp \
  -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'
```

Machine contract: [/openapi.json](https://lazaretto.dev/openapi.json) · [/llms.txt](https://lazaretto.dev/llms.txt) · [API reference](https://lazaretto.dev/docs/api) · server card: [/.well-known/mcp/server-card.json](https://lazaretto.dev/.well-known/mcp/server-card.json)

A verdict describes what we detected in what we analyzed, at the moment we analyzed it. What we get wrong goes in the public [corrections log](https://lazaretto.dev/corrections); what the data cannot tell you is listed in [sources](https://lazaretto.dev/sources).

---

Machine-readable index: https://lazaretto.dev/llms.txt. OpenAPI: https://lazaretto.dev/openapi.json. MCP endpoint: https://lazaretto.dev/mcp. Any page on this site is available as markdown by adding .md to its path.