Package Truth

Stops coding agents from installing packages that do not exist, are deprecated, or have known vulnerabilities, across npm, PyPI, Go, Maven, Cargo, NuGet and RubyGems.

Language models invent package names. In a USENIX Security 2025 study of 16 code models, 19.7% of the packages they recommended did not exist, and attackers now register those invented names ("slopsquatting"). Package Truth checks every dependency before it is installed and gives each one a verdict an agent can act on:

Verdict	Meaning
does_not_exist	No such package, no such version, or no version matching the range: do not install
risky	The version that would be installed is deprecated or has known advisories
verify	Published under 90 days ago or has at most two versions: a possible squat, check before use
ok	No problem found in deps.dev at query time (not a security guarantee)

Give it a whole manifest (package.json, requirements.txt, pyproject.toml, Cargo.toml, go.mod, Gemfile, *.csproj, pom.xml) and it resolves each range to the version an install would pick today, checks it, and lists problems first. No account, no key.

Built and maintained by Arhan Canli. Data from deps.dev (Open Source Insights).

Install

Needs Node.js 20 or newer. No account or key.

Claude Code

claude mcp add package-truth -- npx -y package-truth-mcp

Claude Desktop: download package-truth-mcp-<version>.mcpb from the latest release and open it. The bundle is signed; verify it with gh attestation verify <file> --repo arhancanli/package-truth-mcp.

Any other client (Windsurf, Zed, Cline, Continue and others), in its MCP config file:

{
  "mcpServers": {
    "package-truth": {
      "command": "npx",
      "args": [
        "-y",
        "package-truth-mcp"
      ]
    }
  }
}

Docker

docker build -t package-truth-mcp https://github.com/arhancanli/package-truth-mcp.git && docker run -i --rm package-truth-mcp

Hosted (Streamable HTTP): node src/server.mjs --http serves stateless MCP at POST /mcp (port from PORT, default 3000).

Example

An agent calls check_packages with:

{
  "ecosystem": "npm",
  "packages": [
    {
      "name": "express"
    },
    {
      "name": "request"
    },
    {
      "name": "express",
      "version": "4.17.1"
    },
    {
      "name": "express",
      "version": "99.0.0"
    },
    {
      "name": "left-pad-hallucinated-zz9"
    }
  ]
}

and gets back (recorded from the live server on 2026-09-26):

{
  "ecosystem": "npm",
  "counts": {
    "does_not_exist": 2,
    "risky": 2,
    "verify": 0,
    "ok": 1
  },
  "results": [
    {
      "name": "express",
      "version": "99.0.0",
      "latest": "5.2.1",
      "verdict": "does_not_exist",
      "flags": [
        "version_not_found"
      ],
      "note": "Version 99.0.0 was never published. The latest is 5.2.1."
    },
    {
      "name": "left-pad-hallucinated-zz9",
      "verdict": "does_not_exist",
      "flags": [
        "not_found"
      ],
      "note": "The registry has no package with this name. It may be misspelled or hallucinated; do not install it."
    },
    {
      "name": "request",
      "version": "2.88.2",
      "latest": "2.88.2",
      "verdict": "risky",
      "flags": [
        "deprecated",
        "vulnerable",
        "no_release_in_3_years"
      ],
      "deprecated_reason": "request has been deprecated, see https://github.com/request/request/issues/3142",
      "advisories": [
        "GHSA-p8p7-x288-28g6"
      ],
      "license": "Apache-2.0",
      "first_published": "2011-01-22",
      "latest_published": "2020-02-11",
      "version_count": 126
    },
    {
      "name": "express",
      "version": "4.17.1",
      "latest": "5.2.1",
      "verdict": "risky",
      "flags": [
        "vulnerable"
      ],
      "advisories": [
        "GHSA-qw6h-vgh9-j6wx",
        "GHSA-rv95-896h-c2vc"
      ],
      "latest_advisory_count": 0,
      "license": "MIT",
... (16 more lines)

Tools

Tool	What it does
check_manifest	Checks every dependency in a manifest file's text (package.json, requirements*.txt, pyproject.toml, Cargo.toml, go.mod, Gemfile, *.csproj, pom.xml). Pinned versions are checked exactly; ranges at the version an install would pick today. Problems are listed first.
check_packages	Checks up to 100 packages in one registry: exists, latest version, deprecated, known advisories, licence, age. Verdict each: does_not_exist, risky, verify (new or tiny: possible squat) or ok. Omit version for the latest.
get_advisories	Lists the known security advisories for one package version (latest if omitted): id, title, CVE aliases, CVSS 3 score and link, plus how many affect the latest version.

How it behaves

• Read-only: no tool changes anything outside this process. Manifests are parsed as text; nothing in them is executed or fetched.
• Ranges are resolved like the package manager would (npm and Cargo caret, tilde, x and hyphen ranges; PyPI specifiers including ~= and ==1.2.*; RubyGems ~>). Prereleases are never picked. Maven and NuGet ranges are checked at the latest version and flagged as such.
• Network: HTTPS only, to the hosts listed in package.json under factory.allowHosts, with a deadline, a size cap and bounded retries. Nothing else is contacted, and nothing is logged except unexpected failures (to stderr, without your inputs).
• Results are compact JSON with a matching output schema. Lists say how many items were left out.

Benchmark

Measured 2026-09-26 with gpt-5.4-mini, 10 fixed tasks graded by fixed checks (bench/tasks.json, raw results in bench/results/).

Server	Correct	Input tokens	Output tokens	Tool calls	Median time
This server	10/10	13226	533	10	3.4 s
package-version-check-mcp, the best maintained alternative	7/10	28924	540	10	2.9 s

Performance

Measured 2026-09-26 from Dubai, home connection against the live upstream, Node 24.19.0 (bench/perf.json, scripts/perf.mjs in the factory).

Call	First call	Repeat	Result size
check_packages: 5 npm packages (missing, deprecated, vulnerable, clean)	1556 ms	1.1 ms	1,290 chars
check_packages: 1 PyPI package	1358 ms	0.4 ms	455 chars
check_packages: 1 Go module	1721 ms	1.9 ms	277 chars
check_manifest: package.json, 5 entries	1779 ms	4.4 ms	1,270 chars
check_manifest: requirements.txt, 4 lines	1526 ms	0.8 ms	926 chars
get_advisories: express 4.17.1	2137 ms	0.3 ms	462 chars

First call: a fresh server process, including the TLS connection and the upstream's own time. Repeat: the same call again, answered from the in-process cache, so it shows this server's own overhead.

Tool definitions the model reads on every turn (name, description, input schema): 1,806 characters, against 5,496 for package-version-check-mcp, the best maintained alternative. The full tool list, with the output schemas and annotations clients use to validate results, is 3,899 characters (8,487 for the alternative).

More MCP servers by Arhan Canli

• Actions Check: Checks GitHub Actions workflows: outdated actions, old Node runtimes, retired runners, injection.
• Config Check: Validates config files against their official schemas: tsconfig, compose, workflows, 1,400+ more.
• Cron Check: Explains cron expressions, lists next run times in any time zone, converts between cron dialects.
• Dockerfile Check: Checks Dockerfiles: build-breaking mistakes, base image tags that exist, digests, platforms, EOL.
• Domain Health: Email and domain checks: SPF lookup limits, DKIM keys, DMARC, DNS records, registration expiry.
• End of Life: Is this version still supported? EOL dates, latest patch and upgrade target for 470+ products.
• Internet Standards: RFC sections, status, obsoleted-by chains, errata and IANA registries for coding agents.
• Kube Check: Checks Kubernetes manifests for your version: removed APIs, unknown fields, Pod Security, risks.
• The whole collection, 12 more

License

MIT, Copyright (c) 2026 Arhan Canli.