compare_packages

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

With no annotations, the description carries the full burden. It discloses that the tool generates a detailed analysis including module system, TypeScript support, popularity, maintenance, bundle sizes, and provides a scored recommendation with pros/cons. This goes beyond the schema and makes behavioral expectations clear. It could add more on side effects or limitations, but for a read-only comparison tool, this is adequate.

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 two sentences, front-loaded with the core purpose, then details on what the analysis includes and the output format. Every sentence adds value. The 'IMPORTANT' marker draws attention to key details without excessive length.

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 is simple (one param, no output schema), the description covers the purpose, the comparison dimensions, and the output type comprehensively. It could mention return format explicitly (e.g., JSON structure), but the description's 'comprehensive comparison report' is sufficient for an agent to understand what it returns.

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?

The input schema covers 100% of the single parameter, describing it as an array of package names (2-5). The description adds context for why this parameter is used, but no additional syntactical or format detail beyond the schema. Baseline 3 is appropriate because the schema already does the heavy lifting.

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 function: comparing multiple npm packages side-by-side to answer 'which is better?' or 'pros/cons' questions. It specifies the resource (npm packages) and the action (compare), and distinguishes itself from sibling tools like compare_versions, which is for version comparisons.

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 gives clear context on when to use the tool ('to answer which is better or pros/cons questions'), but it does not explicitly list when not to use it or name alternatives. A more explicit exclusion (e.g., 'not for comparing versions') would make it a 5.

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