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

Annotations already declare readOnlyHint and openWorldHint, so safety profile is covered. The description earns credit for adding behavioral context the annotations don't: the upstream data source (OSV.dev), the per-call price ($0.01 USDC via x402), and the charging semantics ('charged only on success'). It stops short of rate limits or the payment/auth flow detail.

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?

Three short sentences, zero filler, front-loaded with the delivered artifact before source and cost. Every clause carries information an agent needs.

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?

No output schema exists, so the description carries the return-shape burden, which it partially addresses by naming fixed versions and the CVE/GHSA identifiers. With 100% schema coverage and safety annotations, the remaining gap is minor — how the paid response is delivered or whether failures surface differently.

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 all three parameters (name, version, ecosystem) are already documented, including an ecosystem value list. The description adds only that the version must be 'specific,' matching the schema's 'Exact version' — no new parameter-level meaning. Baseline 3 applies.

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?

Names the exact resource returned — known CVE/GHSA vulnerabilities for a specific package version — plus the payoff ('with fixed versions'). No sibling is remotely similar (product recalls, VIN decode, SEC filings), so an agent can select this immediately without ambiguity.

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?

Usage is implied by the purpose (call it when you need vuln data for a pinned package version) but there is no explicit when-to-use, when-not-to-use, or alternative listed. Nothing misleading, just no routing guidance beyond the obvious.

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