NPMScan

Diff two package.json/lockfile snapshots

diff_dependencies

Read-only

Compares two raw snapshots of a package.json, package-lock.json (npm v1-v3), yarn.lock (classic v1 or Berry), or pnpm-lock.yaml — e.g. before/after a PR — and reports which packages were added, removed, or version-bumped. For every added or bumped package (up to 100 per call), also checks whether its resolved version carries a preinstall/install/postinstall/prepare lifecycle script that the before-version did NOT have (installScriptIntroduced, the highest-signal field here — a routine-looking patch bump quietly adding a postinstall is exactly the shape of a compromised-maintainer supply-chain attack) and batch-checks it against OSV.dev, reporting vulnerabilityDelta (introduced/fixed/still-vulnerable/still-clean) rather than just a bare isVulnerable flag. Scope notes: only direct dependencies are diffed for package.json/package-lock.json/pnpm-lock.yaml (their own formats distinguish direct from transitive); yarn.lock has no such distinction, so its side of the diff covers every resolved package in the file — expect a larger added/removed count when diffing a yarn.lock, and check comparisonNote when the two snapshots are different formats. The install-script check is presence-only (read from the registry packument or lockfile metadata, not a tarball content scan) — use analyze_install_script for a deep-dive on anything flagged here. Ideal for a CI gate reviewing a dependency-changing PR.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`after`	Yes	Raw file content of the "after" snapshot — a package.json, package-lock.json (npm v1-v3), yarn.lock (classic v1 or Berry), or pnpm-lock.yaml. Format is auto-detected; before/after may be different formats.
`before`	Yes	Raw file content of the "before" snapshot — a package.json, package-lock.json (npm v1-v3), yarn.lock (classic v1 or Berry), or pnpm-lock.yaml. Format is auto-detected; before/after may be different formats.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`added`	Yes
`changed`	Yes
`removed`	Yes
`summary`	Yes
`truncated`	Yes
`totalAdded`	Yes
`afterFormat`	Yes
`beforeFormat`	Yes
`flaggedCount`	Yes
`totalChanged`	Yes
`totalRemoved`	Yes
`comparisonNote`	Yes
`enrichmentNote`	Yes
`truncationNote`	Yes

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

AddedSep 1, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations only declare readOnlyHint, openWorldHint, and non-destructive. The description adds significant non-obvious behaviors: 100-per-call cap, presence-only install-script check (not tarball scan), direct-vs-transitive diff scoping per format, vulnerabilityDelta granularity, and comparisonNote for mixed formats. No contradiction.

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?

The description is long but every sentence carries meaningful information—supported formats, limit, signal explanation, scope differences, and alternatives. It is well-structured but dense; could be trimmed slightly without losing value.

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?

Given the tool's complexity and that an output schema exists, the description amply covers all critical operational nuances: what it reports, the limit, format-specific scope, how install scripts are checked, and when to delegate to a sibling. Nothing essential is missing.

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 coverage is 100% and both before/after already have detailed descriptions in the schema (raw content, supported formats, auto-detection, may differ). The tool description repeats that but adds no new parameter-level meaning beyond contextualizing the diff workflow. Baseline 3 applies.

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?

Clearly states the verb 'Compares' and the resource: two raw snapshots of package manifests, listing supported formats and the add/remove/version-bump report. It also distinguishes itself from sibling analyze_install_script by explicitly naming it as the deep-dive alternative.

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

Usage Guidelines5/5

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

Explicitly identifies its primary use case ('Ideal for a CI gate reviewing a dependency-changing PR') and gives an alternative ('use analyze_install_script for a deep-dive'). It also provides scope caveats for yarn.lock and mixed-format comparisons, so the agent knows what to expect.

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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TDQS

A4.4/5.0

Disambiguation4/5

Most tools have clearly distinct scopes, such as flat vs. transitive vulnerability checks and per-package vs. GitHub-repo audits. The main ambiguity is that several tools all ultimately report OSV/NVD findings or perform install-script risk checks, though the descriptions do draw clear boundaries and include cross-references to steer selection.

Naming Consistency5/5

Every tool follows a consistent lowercase snake_case verb_noun pattern, e.g. analyze_install_script, check_maintainer_changes, prioritize_remediation. The naming is predictable and makes the action and target of each tool immediately clear.

Tool Count3/5

At 22 tools, the surface is at the heavy end of the rubric and pushes beyond the typical 3-15 well-scoped range. The tools are individually purposeful and broad in coverage, but the count is high enough that an agent faces a large decision space and several workflows that overlap or compose in complex ways.

Completeness5/5

The set covers the full npm supply-chain assessment lifecycle: discovery, metadata lookup, vulnerability scanning, transitive dependency analysis, license checks, install-script analysis, maintainer and provenance checks, SBOM generation, dependency diffs, upgrade simulation, remediation prioritization, and alternative suggestion. There are no obvious dead ends or major missing operations for the stated domain.

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