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

Annotations already declare readOnly/idempotent/openWorld and no destructive behavior, so the safety profile is covered. The description adds useful context beyond that: it checks port 443, auto-checks www for bare domains, and returns findings each with severity, fix, and citation.

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 action and a compact enumeration of checks; the two trailing sentences about www handling and finding structure earn their place. The middle sentence is dense but not padded.

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 compensates by describing the return shape (severity, fix, citation) and the www side-effect. Combined with a fully described input schema, an agent has everything needed to call and interpret this tool.

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%, so the schema already documents domain, detail, and include_www with defaults. The description only lightly reinforces include_www behavior ('Checks www as well when given a bare domain') and adds no syntax not already in the schema. 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?

States a specific verb and resource ('Check the HTTPS certificate and TLS setup of a domain on port 443') and enumerates exactly what is inspected, which cleanly separates it from check_domain_registration, check_email_auth, and check_security_headers.

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 enumerated scope (certificate/TLS checks for one domain), but there is no explicit when-to-use guidance and no mention of the sibling full_domain_report, which likely overlaps. Nothing is misleading, but the agent gets no routing help.

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