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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds value by stating 'Read-only. No side effects. Idempotent.' and listing sources (OSV.dev, deps.dev, npm registry). It also explains the wrapping behavior. No contradictions with annotations.

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 comprehensive but not overly verbose; it front-loads the purpose and provides essential details. It loses a point for being slightly lengthy but remains well-structured and informative.

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 output schema existence, annotations, and the description covering purpose, parameters, usage guidelines, behavioral traits, sources, and fallback behavior, the description is fully complete. It enables an agent to understand when to use, how to use, and what to expect.

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 parameters. The description adds meaning: package_name is described as 'npm package name. Required.' and version is described as 'Optional pinned version — latest resolved if omitted,' which clarifies behavior beyond the schema's 'Package version e.g. 2.28.0. Optional.'

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: providing a SHIP/CAUTION/BLOCK risk brief for npm packages with frontend-specific context, differentiating it from the wrapped security_fetch_package_risk_brief. It specifies the added signals (weekly_downloads, is_ui_component) and explicitly mentions it is restricted to npm.

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 explicitly tells when to use this tool (for npm packages) and when not to ('Use security_fetch_package_risk_brief for non-npm ecosystems'). It also provides a fallback mechanism: calling report_feedback if the response does not serve the user's need.

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