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

Beyond the readOnlyHint/openWorldHint annotations, it discloses access model ('Anonymous, rate-limited per IP'), a refusal condition ('private and reserved addresses are refused'), and the analytical limits of the check ('Reports the advertised policy only' plus 'warnings for ineffective values'). This is real behavioral context the annotations do not carry.

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?

Two sentences, front-loaded with the core purpose and scope, followed by routing and operational caveats. The enumerated checklist is dense but each clause maps to a distinct behavior, so little 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?

With an output schema present, return values need no explanation. The description covers scope, sibling boundaries, auth/rate-limit behavior, and refused targets, leaving nothing an agent needs to invoke it correctly.

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?

There is a single parameter at 100% schema coverage, and the schema already documents 'domain' with an example. The description adds nothing about the parameter beyond what the schema provides, so the baseline 3 is appropriate.

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 gives a specific verb and resource ('Checks a domain's HTTP Strict Transport Security setup') and then enumerates exactly what aspects are inspected (header presence, max-age, includeSubDomains, preload, HTTP-to-HTTPS redirect, preload eligibility, ineffective-value warnings). It is easily distinguished from check_ssl and redirect_check, which it names outright.

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 explicitly bounds the tool's scope with 'Reports the advertised policy only' and routes the agent elsewhere for adjacent concerns: 'the certificate is check_ssl and the redirect chain redirect_check.' That is explicit when-not-to-use guidance with named alternatives.

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