npmTrends

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

The annotations already provide strong behavioral hints (readOnlyHint: true, openWorldHint: true, idempotentHint: true), so the bar is lower. The description adds value by specifying the type of data returned ('download trends and popularity metrics'), which isn't covered by annotations, but doesn't elaborate on rate limits, data freshness, or other operational details that would enhance transparency.

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?

The description is a single, efficient sentence that states the core functionality without any fluff. It's appropriately sized for a tool with clear annotations and good schema coverage, making it easy to parse and understand at a glance.

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?

Given the tool's moderate complexity (2 parameters, no output schema), the description is minimally complete. It covers what the tool does but lacks context about when to use it among siblings or what the output looks like (e.g., format of trends data). With annotations providing safety and idempotency info, it's adequate but leaves gaps in usage guidance.

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?

With 100% schema description coverage, the schema already fully documents both parameters ('packages' and 'period'), including enum values for 'period'. The description doesn't add any meaningful parameter semantics beyond what's in the schema, such as explaining what 'download trends' means or how multiple packages are handled, so it meets the baseline but doesn't exceed it.

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?

The description clearly states the tool's purpose with specific verbs ('Get download trends and popularity metrics') and resources ('for packages'), making it immediately understandable. However, it doesn't explicitly differentiate this tool from its many siblings like 'npmSearch' or 'npmRepoStats', which might also provide related metrics, so it doesn't reach the highest score.

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?

The description provides no guidance on when to use this tool versus alternatives. With 17 sibling tools including 'npmSearch', 'npmScore', and 'npmRepoStats', there's no indication of when this specific trend-focused tool is appropriate or what distinguishes it from other metrics tools, leaving the agent to guess based on the name alone.

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