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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuine context beyond that: it makes an outbound network connection on port 443, caps address probing at up to 4 IPv4 and 4 IPv6 addresses, and notes that ACME renewal-window data is only available for four named CAs—an important conditional an agent would otherwise not know.

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?

One front-loaded sentence with the action first and the reported fields following; every clause carries substantive information. It is dense and the long enumeration requires careful reading, but there is no filler.

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 takes on the job of explaining return values and does so thoroughly—trust/match status, issuer, expiry and days left, lifetime, chain, TLS version, per-address results, and CA-suggested renewal window with its provider restriction. An agent knows what it will get and the limits of that data before calling.

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% and the single parameter is already documented as a public domain name that also accepts a URL (host only). The description adds nothing further about the domain argument, so the baseline 3 applies—the schema is doing the work here.

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 opens with a concrete verb and resource—'Connects to a domain on port 443 and reports its TLS certificate'—and enumerates exactly what is reported (trust, name match, issuer, expiry, chain, TLS version). That is clearly distinct from the sibling check_domain_expiry in substance, but the sibling is never named, so an agent must infer the split rather than being routed to it.

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?

Usage is implied rather than stated: 'connects to a domain' and the mention of public-facing server addresses signal that this applies to live, publicly reachable hosts. There is no explicit when-to-use/when-not-to-use guidance and no reference to check_domain_expiry as the alternative for registration-expiry questions.

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