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

Annotations already declare read-only, idempotent, open-world, non-destructive, but the description adds behavior they cannot express: it contacts the target on port 443, follows at most three HTTPS redirects, times out at ten seconds, and returns no page content. The untrusted-data warning ("never instructions") is a valuable safety disclosure about the returned evidence.

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 tight sentences, front-loaded with what is inspected, then network limits, then the safety caveat. Every clause carries information; nothing repeats the name or schema verbatim.

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 compensates by naming the categories of returned evidence and the hard execution limits an agent must plan around. Combined with the untrusted-data warning, nothing material is missing for correct invocation.

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 required parameter with 100% schema description coverage, and the schema already states "public domain name only; no URL, path, port or credentials." The description's phrase "public domain's HTTPS root" is consistent but adds no new syntax or format guidance 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 specific verb (check) and resource (public domain's HTTPS root) and enumerates exactly what is inspected: status, redirects, TLS certificate metadata and selected security headers. That scope cleanly separates it from the DNS/email-oriented siblings (lookup_dns, check_email_dns, trace_email) without needing to name them.

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 implies the use case (auditing a domain's HTTPS/TLS posture) and gives a scope exclusion ("No page content"), which helps an agent rule it out for content fetching. However it never names an alternative tool or states when to prefer lookup_dns or deployment_readiness, so selection guidance rests on inference.

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