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

Even though annotations already indicate read-only and idempotent behavior, the description adds substantial behavioral context: KEV-first ordering, verbatim OSV range output, the events/fixed/affected_through projection, the explicit refusal to evaluate version membership, and the coverage caveat that absence is not evidence of safety. This goes well beyond what annotations 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 dense but every sentence earns its place: purpose, input modes, output format, version-range semantics, and an important coverage caveat. The main action is front-loaded and there is no filler or repetition of the schema.

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?

There is no output schema, so the description correctly takes on the burden of explaining return values. It covers what is returned (CVE list, KEV-first), how version ranges are represented (fixed vs affected_through), and what the tool does not do. For a read-only package advisory lookup, nothing critical 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 coverage is 100%, so the baseline is 3. The description adds meaningful semantics beyond the schema by clarifying purl vs ecosystem+name usage, flagging Maven group:artifact format, and giving concrete examples like pkg:npm/lodash, which helps an agent construct correct parameter combinations.

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 opens with a specific verb and resource: 'CVEs affecting one open-source package' and immediately distinguishes the query modes (purl vs ecosystem + name). It clearly separates this from siblings like search_cves and get_cve by emphasizing a single package's advisory list.

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?

It gives clear context for when to use the tool: when you need CVEs for one package, identified by purl or ecosystem + name. It does not explicitly name alternatives or exclusions, but the package-scoped scenario is unmistakable and no misleading guidance is present.

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