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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds genuinely new context — that trust is not asserted, the pricing model, x402/Base payment, the prepaid header option, and the free-call allowance. That is material behavioral and auth context beyond the structured fields.

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?

Front-loaded with the core question and the returned field list, then scoping and payment terms. Dense but largely waste-free; the pricing sentence is long though relevant to invocation.

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 the return values needn't be spelled out (it lists them anyway), annotations cover the safety profile, and the auth/cost caveat is given. Only the lack of when-to-use routing leaves a small gap.

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 coverage is 100% with host and port documented, so the schema carries the parameter burden; the description only restates that host is required and adds no format or port-range semantics. 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?

Names a specific verb and resource (TLS probe for a host's certificate) and enumerates the returned fields (subject, issuer, validFrom/validTo, daysRemaining, expired/expiringSoon, fingerprint). It is clearly distinguishable from sibling infra tools like dns_lookup or domain_check.

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 (check whether a host's cert expires) and it states the required input and a key scope caveat ('chain trust is not asserted'), but it never names when to prefer this over adjacent siblings such as url_risk or proxy_check, nor any exclusion conditions.

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