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

Annotations (readOnlyHint=true, destructiveHint=false, idempotentHint=true, openWorldHint=true) already indicate safe, read-only behavior. The description adds valuable behavioral details: returns ranked results with quality, popularity, maintenance scores, download counts, dependents, license, and publisher. This goes beyond the schema and annotations, providing rich context about output.

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 long, front-loaded with the core purpose, and packs substantial information (scale, return fields, examples) without wasted words. Every sentence earns its place.

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 rich annotations, well-documented schema, and presence of an output schema, the description is sufficiently complete. It covers the tool's purpose, behavior, and output in a compact form, leaving no critical gaps for an AI agent to understand its usage.

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 100% with descriptions for both params (query and size). The description adds example queries but does not provide new semantic information about the parameter schema. Since the schema already well-documents the parameters, the description's contribution here is neutral.

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 searches npm packages by keyword, specifying the scale (2.1M+ packages) and the return fields (quality, popularity, maintenance scores, etc.). It effectively distinguishes itself from sibling tools like npm.packages.info or npm.packages.downloads, which are for specific package details or download stats, not search.

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 example queries in parentheses, implicitly guiding when to use this tool for discovery. It does not explicitly mention alternatives or when not to use, but the context of sibling tool names (e.g., npm.packages.info) provides indirect guidance. A clear statement of alternatives would improve this score.

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