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

Annotations already establish the safe-read profile (readOnly, idempotent, non-destructive, openWorld), and the description goes well beyond them by disclosing data provenance (OSV.dev and deps.dev), the default behavior when version is omitted (latest version is checked), and an explicit freshness caveat that newly published malware may not yet be listed. Those are exactly the operational traits an agent needs and that structured fields cannot convey.

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?

Front-loaded with purpose, then return contents, then usage triggers and a caveat; every sentence carries information and there is no filler. It is dense as a single long paragraph, which slightly hurts scannability, but nothing is wasted.

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 must carry the return-value burden and it does, enumerating each returned field including the fix version and minimum clearing version. Combined with multi-ecosystem coverage, the omission default, and the data-source caveat, an agent has everything needed to call and interpret it.

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%, with the schema itself documenting the ecosystem aliases and the version default ("Omit to check the latest release"). The description restates that default and the ecosystem list but adds no new syntax, format, or constraint information beyond the schema, so the 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?

States a concrete verb ("Check") and resource ("one open-source package") and enumerates the ecosystems covered, then lists exactly what the result contains (malware flag, vulnerabilities, fix versions, latest stable version, licences, Scorecard). The word "one" implicitly separates it from the bulk siblings check_dependencies and check_lockfile, so an agent can route correctly without opening a schema.

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?

Gives explicit trigger phrasings ("is <package> safe?", "is it malware?", "should I upgrade?") and a concrete precondition: call it before recommending any package or version to install, with install commands listed. It does not name the sibling alternatives (check_dependencies, check_lockfile, get_vulnerability) or say when NOT to use it, so it stops short of a full when/when-not/alternatives statement.

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