NPM Sentinel MCP

npmSize

Read-onlyIdempotent

Check npm package size including dependencies and bundle size for up to 25 packages in one call.

Instructions

Get package size information including dependencies and bundle size

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "packages": "<packages>"
    },
    "name": "npmSize"
  }
}

Input Schema

Name	Required	Description	Default
`packages`	Yes	List of package names to get size information for
`ignoreCache`	No	Force a fresh lookup, ignoring the cache

Output Schema

Name	Required	Description	Default
`message`	No
`results`	No
`summary`	No

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.24.0Jul 28, 2026
Removedv1.23.0Jul 25, 2026
Changed2 schema fields changedv1.20.0Jul 13, 2026
- removedInput schema / additionalProperties
```
Removed value: -false
```
- addedInput schema / properties / ignoreCache
```
Added value: +{
+  "description": "Force a fresh lookup, ignoring the cache",
+  "type": "boolean"
+}
```
First observedv1.0.0Aug 14, 2025

TDQS

A3.8/5.0

Behavior4/5

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

The description adds value beyond annotations by specifying that size information includes dependencies and bundle size. It is consistent with the readOnlyHint and idempotentHint annotations, providing useful behavioral context without contradiction.

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

Conciseness5/5

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

The description is a single, efficient sentence that conveys the core purpose without unnecessary words. It is front-loaded and earns its place.

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

Completeness4/5

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

For a tool with a simple 2-parameter schema and an output schema available, the description is sufficient. It explains the main function. Minor omission: it does not mention the underlying service (Bundlephobia) which is only in annotations.

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?

Full schema coverage (100%) means the input schema already describes both parameters. The description does not add additional parameter-level details, so a baseline score 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?

The description clearly states the tool's function: 'Get package size information including dependencies and bundle size.' It specifies the resource and scope, and is distinct from sibling tools like npmVersions or npmDeps.

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

Usage Guidelines2/5

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

No guidance is provided on when to use this tool versus alternatives. The description lacks context for appropriate usage or exclusions, leaving the agent to infer from the tool name and siblings alone.

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