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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond annotations: it queries an external service, returns a distilled answer rather than raw data, and specifies the output fields including fixedVersion, CVE aliases, and plain-language summaries. This is substantial transparency for a read-only tool.

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 with no filler. It front-loads the core action and scope, then delivers high-value output and usage context. 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 schema, existing output schema, and annotations, the description adds exactly what is missing: when to use it, what the returned answer looks like, and the key distinction that it is not a raw advisory dump. Nothing needed for safe invocation is missing.

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 description coverage is 100%, so parameter semantics are already fully documented in the schema. The description adds a helpful real-world example (lockfile pin check) and reinforces that version is optional, but it does not carry the parameter-documentation burden. Baseline 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 specific verb and resource: querying OSV.dev for known vulnerabilities affecting an npm package. It further distinguishes itself from a raw advisory dump by promising a direct isVulnerable/highestSeverity answer, and its exact-version scoping differentiates it from broader advisory tools like get_latest_advisories.

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 for when to use the tool: 'Use before recommending, installing, or upgrading a package,' and provides a concrete use case for checking a lockfile-pinned version. However, it does not explicitly mention the sibling batch_query_vulnerabilities or state when not to use this tool, so it stops short of full exclusion guidance.

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