pkgproof

Verify package

verify_package

Verify an npm or PyPI package before installing. Check advisories, install scripts, typosquatting, scope/repo mismatches, and release changes to get safe, caution, block, or does_not_exist verdicts.

Instructions

Verify an npm or PyPI package before installing it. Runs up to nine checks covering advisories, install scripts, typosquat and combosquat names, scope and declared-repository checks, and how the release differs from its predecessors, and answers safe, caution, block or does_not_exist with every reason labelled as fact or heuristic against its source. One call is one verification: the first each day is free, and later ones cost $0.05 in USDC when a wallet is configured.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`name`	Yes	Package name: left-pad or @scope/thing on npm, requests on PyPI.
`version`	No	Exact version to verify. Omit to verify the package rather than one release.
`ecosystem`	No	Package ecosystem: npm or pypi.	npm

Output Schema

TableJSON Schema

Name	Required	Description
`name`	Yes
`reasons`	Yes	Every reason behind the verdict.
`sources`	Yes	The datasets consulted, by name and URL.
`verdict`	Yes
`version`	Yes	The version verified, or null if none was given.
`dist_tag`	No	The dist-tag a version-less request resolved through; null when a version was given.
`ecosystem`	Yes
`checked_at`	Yes	When the verdict was computed, ISO 8601 UTC.
`resolved_version`	No	The release the checks ran against: the version asked for, or the registry's latest.

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedv0.2.1Oct 16, 2026

changedInput schema / properties / ecosystem / description

Previous value: -"Package ecosystem. Only npm is supported."New value: +"Package ecosystem: npm or pypi."

changedInput schema / properties / ecosystem / enum

Previous value: -[
-  "npm"
-]New value: +[
+  "npm",
+  "pypi"
+]

changedInput schema / properties / name / description

Previous value: -"Package name, scoped or not: left-pad, @scope/thing."New value: +"Package name: left-pad or @scope/thing on npm, requests on PyPI."

Changed2 schema fields changedv0.1.12Oct 14, 2026

addedOutput schema / properties / dist_tag

Added value: +{
+  "description": "The dist-tag a version-less request resolved through; null when a version was given.",
+  "type": [
+    "string",
+    "null"
+  ]
+}

addedOutput schema / properties / resolved_version

Added value: +{
+  "description": "The release the checks ran against: the version asked for, or the registry's latest.",
+  "type": [
+    "string",
+    "null"
+  ]
+}

First observedv0.1.0Sep 8, 2026

TDQS

A4.4/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the annotations by disclosing the check inventory, the four possible verdicts, and that every reason is labelled as fact or heuristic against its source. Critically, it discloses cost behavior (first call each day free, later calls $0.05 USDC when a wallet is configured), which an agent must know before invoking. The readOnlyHint=false and openWorldHint=true annotations are consistent with a tool that performs live external lookups and can charge a wallet.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose and scope are front-loaded in the first sentence, with mechanism and cost following. The enumeration of nine checks is dense but each item is substantive; the cost sentence is longer than strictly necessary but earns its place since pricing affects invocation decisions.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with an output schema, the description need not explain return structure, and it still characterizes the verdict vocabulary and fact/heuristic labelling. Combined with the documented checks, verdict outcomes, and payment terms, an agent has everything needed to decide whether and how to call it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents name formats (left-pad, @scope/thing, requests), the version-omission semantics, and the npm/pypi enum with default. The description adds only ecosystem context (npm or PyPI) that the schema already carries, so the baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Verify an npm or PyPI package') plus the exact scope of work (up to nine checks across advisories, install scripts, typosquat/combosquat names, scope/repository checks, and release diffs). It also names the possible outcomes (safe, caution, block, does_not_exist), so an agent knows precisely what the call produces. There are no siblings to disambiguate against, but the purpose is unambiguous on its own.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase 'before installing it' gives a clear triggering context, and 'One call is one verification' defines the unit of invocation, which helps an agent decide when to call once vs. multiple times. It does not state a when-not-to-use case (e.g., cached results, already-installed packages), but with no alternatives available that gap is minor.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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