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

Annotations declare readOnlyHint=true and openWorldHint=true, so the safety profile is already covered. The description still adds non-obvious behavior: 'Each host that answers counts as one result,' which signals per-host result/billing accounting and that non-responding hosts are silently excluded. It omits timeout, retry, and failure-handling behavior, keeping it below a 5.

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?

A single information-dense sentence that front-loads the core question (post-quantum key exchange) before the secondary checks. The trailing result-counting clause is slightly grafted on, but nothing 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 no output schema, the description still conveys the shape of the result (per-domain findings plus a letter grade) and the result-counting rule. It does not explain behavior for unreachable hosts or what a partial/failed scan returns, which is the remaining gap for a network-facing scanner.

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 one parameter and schema coverage is 100%: the schema documents the 1-20 host array and that URLs are accepted. The description adds nothing about host syntax or the array cap, so the baseline 3 for schema-documented parameters 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?

The description states a precise verb and resource ('Check whether domains use post-quantum TLS key exchange') and enumerates the exact signals inspected (X25519MLKEM768/ML-KEM, preferred groups, TLS 1.2/1.3, certificate algorithms/expiry, HSTS, letter grade). This is unmistakably distinct from every sibling (domain_whois, tech_stack, etc.).

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 by the subject matter — an agent can infer this is the tool to call when assessing a domain's post-quantum TLS posture. However, there is no explicit when-to-use/when-not-to-use guidance and no routing to alternatives (e.g., domain_whois for registration data). Adequate but incomplete.

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