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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description adds the materially important caveat that the flaw list is curated and absence of findings is not proof of safety. This prevents an agent from overstating a clean result. It does not describe the shape of the response (e.g., finding entries or severity), which is the remaining gap for a tool with no output schema.

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, front-loaded with the purpose, followed by input guidance and the caveat. Each sentence carries distinct, actionable information with no redundancy.

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?

For a two-parameter read-only lookup, the description covers purpose, input acquisition, and result-interpretation limits, which is close to sufficient. With no output schema, it could say more about what a finding looks like, but the essential information an agent needs to call it correctly is present.

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 the baseline is 3; the description earns above baseline by clarifying that 'version' must be exact and by pointing to `node --version` / `php --version` as the source, which guards against ranges or partial versions. It still does not enumerate the accepted runtime values beyond the schema's 'node or php' hint.

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 names a specific verb ('Checks') and a precisely scoped resource ('a Node.js or PHP version against known security flaws in the runtime itself'), and the phrase 'in the runtime itself' implicitly separates it from the sibling check_package/check_packages/check_platform tools. An agent can distinguish this tool from its siblings without opening any 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?

It gives concrete usage direction: 'Use with the exact version, for example from `node --version` or `php --version`,' which tells the agent how to obtain valid input. The limitation 'no findings doesn't prove a version is safe' sets expectations for interpreting results. It does not explicitly name when to prefer check_package or check_platform instead, so it stops short of a full 5.

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