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

Annotations already declare readOnly, idempotent, non-destructive, and open-world behavior, so the safety profile needs no restating. The description adds the underlying mechanism (UNPKG ?meta) and the important trait that results reflect real archive contents rather than inference, but says nothing about failure modes for unresolvable packages or truncation when limit is hit.

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

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

Two tight sentences with the action first and the usage constraint second; nothing is redundant and every clause carries information.

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

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

With an output schema present and rich annotations, the description need not explain return values, and it covers scope, source, and usage. It is slightly thin on edge cases (nonexistent package, limit truncation) for a tool whose whole purpose is to be the authoritative path source.

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

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

Schema coverage is 75% and documents path, limit, and version defaults/resolution, so the schema carries most parameter meaning. The description only reinforces that the version may be 'exact or resolvable' and leaves the bare 'package' parameter to the schema.

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

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

States a specific verb and resource ('List the real files inside ... a package version') plus the data source ('via UNPKG ?meta'), which is enough to tell it apart from URL-building or resolution siblings. It stops short of explicitly naming which sibling to use instead when you already know a path (e.g., build_file_url).

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

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

'Use this before choosing a file path; never guess paths' gives a clear activation condition and an explicit prohibition. It does not name alternative tools or state what to do when the package/version cannot be resolved, so the routing guidance is strong but not exhaustive.

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