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

Beyond the annotations (readOnly, openWorld, idempotent), the description discloses valuable behaviors: parallel fan-out with registry=all, returning an array vs. a single package, and silently dropping missing registries. It also describes the unified Package shape across registries, giving the agent a clear model of what will happen. This exceeds what annotations alone provide.

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 three sentences with a front-loaded clear purpose. Every sentence adds essential context: unified shape, name format handling, and behavior of registry=all. No filler or redundancy, making it easy to parse quickly.

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 complexity (multi-registry, variable output shape) and no output schema, the description explains the return shape for both modes (single vs. array), the unified shape, and edge cases (missing registries dropped). It covers name formats for all registries, making it sufficiently complete for an agent to invoke correctly.

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?

Input schema covers both parameters 100%, including name format details and registry enum. The description largely restates this information with examples but adds no significant new meaning beyond the schema. Behavioral notes like 'missing registries are silently dropped' relate to output, not parameter semantics. Since schema coverage is high, a baseline of 3 is appropriate.

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 states a clear, specific purpose: 'Full normalized details for one package by registry + name' with a unified Package shape. It explicitly distinguishes itself from sibling tools by covering multiple registries and a unified output shape, so the agent knows exactly what this tool provides versus alternatives like get_downloads or get_versions.

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 clearly implies usage for retrieving normalized package details across registries, with explicit notes on the registry parameter behavior. It does not explicitly state 'use this instead of X', but the context is unambiguous and differentiates from siblings. A 4 is appropriate because exclusions or when-not-to-use are not spelled out.

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