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

Annotations already establish read-only and non-destructive behavior, so the description adds valuable context: the tool uses a 'Korean network probe' for legacy TLS detection, checks specific security headers, and returns 'per-item pass/warn/fail and an overall grade'. This goes beyond the annotation safety profile and clarifies scope and output behavior.

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 a single dense sentence with a front-loaded purpose and an early exclusion note ('no port scanning'). It packs a lot of specific detail into a structured list format without redundant wording, though it is slightly long.

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?

With no output schema, the description appropriately discloses the return shape ('per-item pass/warn/fail and an overall grade'). It covers the main checks, the network probe behavior, and output format. It does not discuss error cases or timing, but for a single-parameter read-only tool this is sufficient.

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?

The only parameter, domain, is fully described in the schema ('Domain name, e.g. example.com'), giving 100% schema coverage. The description does not add parameter-level detail, but none is needed because the schema already covers it; this meets the baseline of 3.

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 clearly states a specific verb and resource: 'Security posture check of a web server', then enumerates exactly what is covered (TLS, headers, redirect, certificate strength). It also distinguishes itself from siblings by explicitly excluding port scanning and focusing on posture rather than DNS or certificate-only checks.

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: for a security posture assessment of a web server, including an explicit exclusion of port scanning. It does not name sibling alternatives such as check_certificate for deeper cert details, so it stops short of explicit routing guidance.

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