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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable context beyond that: it performs a live network connection to the target, discloses the specific signals returned (chain trust, hostname match, TLS version/cipher, HSTS, OCSP stapling, expiry), and uniquely discloses a cost of 10 credits. It doesn't discuss failure modes (unreachable host, timeout) or rate limits.

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 compact paragraph, front-loaded with the action and followed by the return payload and cost. The opening 'SSL Certificate Checker: SSL Checker is an SSL certificate API that...' redundantly restates the tool name and title before getting to the point.

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?

An output schema exists, so return values need not be spelled out, yet the description still summarizes the key result categories, and it adds the credit cost that no structured field conveys. Missing only edge-case behavior for unreachable hosts or invalid domains, which for a one-parameter read-only checker is a minor 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?

There is a single parameter with 100% schema description coverage, so the schema already says it is 'the domain of the website to check the SSL certificate of' with an example. The description adds only the fact that the check is performed live against the domain; it doesn't clarify whether a bare hostname vs a URL with scheme/port is accepted.

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+resource: connects to a website and checks its live SSL certificate, returning chain validity, hostname match, TLS version/cipher and expiry signals. That is far more specific than a bare restatement of the name. It does not, however, differentiate from close siblings such as TLSChecker or DomainExpiration, which an agent could plausibly confuse with this tool.

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 capability list ('checks its live certificate in seconds'), so an agent can infer that it should be called when certificate validity/expiry matters. There is no explicit when-to-use, when-not-to-use, or named alternative such as TLSChecker or DomainExpiration.

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