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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds only the purpose-level detail ('details and expiry') without extra behavioral context like output format, latency, or network behavior, which is what would be needed to go beyond annotations.

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?

The description is two sentences, front-loaded with the action and resource, then immediately followed by a usage rationale. Every word earns its place with no filler or redundancy.

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?

For a simple one-parameter read-only lookup, the description sufficiently conveys the scope and use case. The absence of an output schema is mitigated by the straightforward nature of the tool, though 'details' remains somewhat vague as to what specific certificate data is returned.

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?

The input schema covers the single 'domain' parameter with a description ('Domain to check') at 100% coverage. The tool description merely echoes 'for a domain', adding no essential meaning beyond what the schema already provides, so baseline score is appropriate.

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 specific action ('Check SSL certificate details and expiry') and resource (domain), making the purpose clear. However, it doesn't explicitly differentiate from the closely named sibling tool lookup_ssl_cert_expiry, so it lacks distinct sibling differentiation.

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 gives clear when-to-use context: 'Use when verifying HTTPS configuration or checking certificate validity.' It provides a solid usage context but does not mention exclusions or when to prefer an alternative such as lookup_ssl_cert_expiry.

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